Tu vas découvrir le nombre dérivé, un concept super... Show more
Histoire
Philosophie
Français
HGGSPSign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
21
•
Updated Apr 4, 2026
•
Nombre Dérivé et Applications Pratiques
1 / 10
Le nombre dérivé - Introduction
Le nombre dérivé est partout autour de toi ! Imagine que tu regardes la courbe d'une fonction sur ton écran - le nombre dérivé te dit exactement à quelle vitesse cette courbe monte ou descend à n'importe quel point.
Pour le calculer, on utilise d'abord le taux d'accroissement. C'est la formule magique : /h. Cette formule compare la fonction entre deux points très proches.
💡 Astuce pratique : Le taux d'accroissement, c'est comme calculer la vitesse moyenne entre deux feux rouges - sauf qu'ici on s'intéresse aux fonctions !
Exercice 1 - Fonction quadratique
Avec la fonction f(x) = x² - 3x + 1, tu vas voir que les calculs deviennent plus simples qu'ils n'y paraissent ! D'abord, on trouve le taux d'accroissement : 2a + h - 3.
Ensuite, pour obtenir le nombre dérivé f'(a), on fait tendre h vers 0. Résultat : f'(a) = 2a - 3. C'est tout !
Pour l'équation de la tangente au point x = 2, on applique la formule y = f'(a) + f(a). Avec nos calculs, ça donne y = x - 3.
💡 Rappel important : La tangente "touche" la courbe en un seul point et a la même pente que la courbe à cet endroit !
Exercice 2 - Interprétation graphique
Quand on te donne une tangente avec son équation y = -2x + 5 au point A(1;3), tu peux en tirer plein d'infos ! Le point A nous dit directement que g(1) = 3.
Le coefficient directeur -2 de la tangente, c'est exactement la valeur de g'(1). Donc g'(1) = -2. Simple comme bonjour !
Puisque g'(1) = -2 < 0, la fonction est décroissante au voisinage du point A. Un nombre dérivé négatif = fonction qui descend !
💡 Truc de mémorisation : Coefficient directeur positif → fonction qui monte, négatif → fonction qui descend !
Exercice 3 - Application physique
Avec un projectile de hauteur h(t) = -5t² + 20t + 1, tu découvres que la vitesse instantanée est la dérivée de la hauteur ! Donc v(t) = -10t + 20.
À t = 1 seconde, la vitesse est v(1) = 10 m/s. Le projectile monte encore à ce moment-là !
Pour trouver la hauteur maximale, on cherche quand v(t) = 0. Ça donne -10t + 20 = 0, donc t = 2 secondes. À ce moment précis, le projectile s'arrête de monter avant de redescendre.
💡 Astuce physique : En physique, la dérivée de la position donne la vitesse. Quand la vitesse = 0, on est à un extremum !
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content: test de la première dérivée
Most popular content in Maths
Fiches récapitulatives spé maths - TOUT le programme de terminale
Ces fiches vont vous sauver pour le bac de spé maths! :)
MathsTle
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5
App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Nombre Dérivé et Applications Pratiques
Tu vas découvrir le nombre dérivé, un concept super utile pour comprendre comment les fonctions changent ! C'est comme mesurer la vitesse d'une voiture à un instant précis ou trouver la pente d'une montagne à un endroit donné.
Le nombre dérivé - Introduction
Le nombre dérivé est partout autour de toi ! Imagine que tu regardes la courbe d'une fonction sur ton écran - le nombre dérivé te dit exactement à quelle vitesse cette courbe monte ou descend à n'importe quel point.
Pour le calculer, on utilise d'abord le taux d'accroissement. C'est la formule magique : /h. Cette formule compare la fonction entre deux points très proches.
💡 Astuce pratique : Le taux d'accroissement, c'est comme calculer la vitesse moyenne entre deux feux rouges - sauf qu'ici on s'intéresse aux fonctions !
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Exercice 1 - Fonction quadratique
Avec la fonction f(x) = x² - 3x + 1, tu vas voir que les calculs deviennent plus simples qu'ils n'y paraissent ! D'abord, on trouve le taux d'accroissement : 2a + h - 3.
Ensuite, pour obtenir le nombre dérivé f'(a), on fait tendre h vers 0. Résultat : f'(a) = 2a - 3. C'est tout !
Pour l'équation de la tangente au point x = 2, on applique la formule y = f'(a) + f(a). Avec nos calculs, ça donne y = x - 3.
💡 Rappel important : La tangente "touche" la courbe en un seul point et a la même pente que la courbe à cet endroit !
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Exercice 2 - Interprétation graphique
Quand on te donne une tangente avec son équation y = -2x + 5 au point A(1;3), tu peux en tirer plein d'infos ! Le point A nous dit directement que g(1) = 3.
Le coefficient directeur -2 de la tangente, c'est exactement la valeur de g'(1). Donc g'(1) = -2. Simple comme bonjour !
Puisque g'(1) = -2 < 0, la fonction est décroissante au voisinage du point A. Un nombre dérivé négatif = fonction qui descend !
💡 Truc de mémorisation : Coefficient directeur positif → fonction qui monte, négatif → fonction qui descend !
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Exercice 3 - Application physique
Avec un projectile de hauteur h(t) = -5t² + 20t + 1, tu découvres que la vitesse instantanée est la dérivée de la hauteur ! Donc v(t) = -10t + 20.
À t = 1 seconde, la vitesse est v(1) = 10 m/s. Le projectile monte encore à ce moment-là !
Pour trouver la hauteur maximale, on cherche quand v(t) = 0. Ça donne -10t + 20 = 0, donc t = 2 secondes. À ce moment précis, le projectile s'arrête de monter avant de redescendre.
💡 Astuce physique : En physique, la dérivée de la position donne la vitesse. Quand la vitesse = 0, on est à un extremum !
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
0
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Practice Test ✓ Essay Outlines
Practice Test
Quiz
Flashcards
Essay
Most popular content: test de la première dérivée
Most popular content in Maths
Fiches récapitulatives spé maths - TOUT le programme de terminale
Ces fiches vont vous sauver pour le bac de spé maths! :)
MathsTle
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5
App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user