# chain rule examples basic calculus

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For this problem we clearly have a rational expression and so the first thing that we’ll need to do is apply the quotient rule. All it's saying is that, if you have a composite function and need to take the derivative of it, all you would do is to take the derivative of the function as a whole, leaving the smaller function alone, then you would multiply it with the derivative of the smaller function. We know that. This function has an “inside function” and an “outside function”. Let’s keep looking at this function and note that if we define. Recall that the outside function is the last operation that we would perform in an evaluation. imaginable degree, area of Here they are. I will write down what's called the … All other trademarks and copyrights are the property of their respective owners. Solution: The derivatives of f and g aref′(x)=6g′(x)=−2.According to the chain rule, h′(x)=f′(g(x))g′(x)=f′(−2x+5)(−2)=6(−2)=−12. Here’s what you do. Hint : Recall that with Chain Rule problems you need to identify the “inside” and “outside” functions and then apply the chain rule. The chain rule allows us to differentiate composite functions. Okay. Most of the basic derivative rules have a plain old x as the argument (or input variable) of the function. Get the unbiased info you need to find the right school. © copyright 2003-2021 Study.com. https://study.com/.../chain-rule-in-calculus-formula-examples-quiz.html 1/cos(x) is made up of 1/g and cos(): f(g) = 1/g; g(x) = cos(x) The Chain Rule says: the derivative of f(g(x)) = f’(g(x))g’(x) The individual derivatives are: f'(g) = −1/(g 2) g'(x) = −sin(x) So: (1/cos(x))’ = −1/(g(x)) 2 × −sin(x) = sin(x)/cos 2 (x) Note: sin(x)/cos 2 (x) is also tan(x)/cos(x), or many other forms. Suppose that we have two functions $$f\left( x \right)$$ and $$g\left( x \right)$$ and they are both differentiable. The square root is the last operation that we perform in the evaluation and this is also the outside function. c The outside function is the logarithm and the inside is $$g\left( x \right)$$. 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(a) w=e^{2xy} , x=\sin t , y=\cos t ; t=0. To learn more, visit our Earning Credit Page. Select a subject to preview related courses: Once I've done that, my function looks very easy to differentiate. Not sure what college you want to attend yet? When the argument of a function is anything other than a plain old x, such as y = sin (x 2) or ln10 x (as opposed to ln x), you’ve got a chain rule problem. We’ve already identified the two functions that we needed for the composition, but let’s write them back down anyway and take their derivatives. $F'\left( x \right) = f'\left( {g\left( x \right)} \right)\,\,\,g'\left( x \right)$, If we have $$y = f\left( u \right)$$ and $$u = g\left( x \right)$$ then the derivative of $$y$$ is, In this case we need to be a little careful. The same thing is true for multivariable calculus, but this time we have to deal with more than one form of the chain rule. In the previous problem we had a product that required us to use the chain rule in applying the product rule. What we needed was the chain rule. In the Derivatives of Exponential and Logarithm Functions section we claimed that. Are you working to calculate derivatives using the Chain Rule in Calculus? It can't help you in those instances. We just left it in the derivative notation to make it clear that in order to do the derivative of the inside function we now have a product rule. Buy my book! I get 8u^7. Look at this example: The first function is a straightforward function. Now contrast this with the previous problem. You can test out of the That was a mouthful and thankfully, it's much easier to understand in action, as you will see. We are thankful to be welcome on these lands in friendship. Find the derivative of the following functions a) f(x)= \ln(4x)\sin(5x) b) f(x) = \ln(\sin(\cos e^x)) c) f(x) = \cos^2(5x^2) d) f(x) = \arccos(3x^2). The lands we are situated on are covered by the Williams Treaties and are the traditional territory of the Mississaugas, a branch of the greater Anishinaabeg Nation, including Algonquin, Ojibway, Odawa and Pottawatomi. Create an account to start this course today. (b) w=\sqrt[3]{xyz} , x=e^{-6t} , y=e^{-3t} , z=t^2 ; t = 1 . Second, we need to be very careful in choosing the outside and inside function for each term. Also learn what situations the chain rule can be used in to make your calculus work easier. Solution: h(t)=f(g(t))=f(t3,t4)=(t3)2(t4)=t10.h′(t)=dhdt(t)=10t9,which matches the solution to Example 1, verifying that the chain rulegot the correct answer. Visit the AP Calculus AB & BC: Help and Review page to learn more. The chain rule states that the derivative of f (g (x)) is f' (g (x))⋅g' (x). Notice as well that we will only need the chain rule on the exponential and not the first term. What about functions like the following. The chain rule states that the derivative of f(g(x)) is f'(g(x))_g'(x). See if you can see a pattern in these examples. A man 6 ft tall walks away from the pole with a speed of 5 ft/s along a straight path. So it can be expressed as f of g of x. Each of these forms have their uses, however we will work mostly with the first form in this class. courses that prepare you to earn The chain rule now tells me to derive u. Therefore, the outside function is the exponential function and the inside function is its exponent. This is to allow us to notice that when we do differentiate the second term we will require the chain rule again. In many functions we will be using the chain rule more than once so don’t get excited about this when it happens. Once you get better at the chain rule you’ll find that you can do these fairly quickly in your head. Anyone can earn Chain Rule: The General Power Rule The general power rule is a special case of the chain rule. So let's consider a function f which is a function of two variables only for simplicity. d $$g\left( t \right) = {\sin ^3}\left( {{{\bf{e}}^{1 - t}} + 3\sin \left( {6t} \right)} \right)$$ Show Solution If z is a function of y and y is a function of x, then the derivative of z with respect to x can be written \frac{dz}{dx} = \frac{dz}{dy}\frac{dy}{dx}. The general form of Leibniz's Integral Rule with variable limits can be derived as a consequence of the basic form of Leibniz's Integral Rule, the Multivariable Chain Rule, and the First Fundamental Theorem of Calculus. That will often be the case so don’t expect just a single chain rule when doing these problems. The following diagram gives the basic derivative rules that you may find useful: Constant Rule, Constant Multiple Rule, Power Rule, Sum Rule, Difference Rule, Product Rule, Quotient Rule, and Chain Rule. We’ll not put as many words into this example, but we’re still going to be careful with this derivative so make sure you can follow each of the steps here. We identify the “inside function” and the “outside function”. You will know when you can use it by just looking at a function. The formulas in this example are really just special cases of the Chain Rule but may be useful to remember in order to quickly do some of these derivatives. This is a product of two functions, the inverse tangent and the root and so the first thing we’ll need to do in taking the derivative is use the product rule. Use the Chain Rule to find partial(z)/partial(s) and partial(z)/partial(t). These tend to be a little messy. Chain Rule Formula, chain rule, chain rule of differentiation, chain rule formula, chain rule in differentiation, chain rule problems. I can definitely differentiate u^8. So, in the first term the outside function is the exponent of 4 and the inside function is the cosine. Here’s the derivative for this function. A formula for the derivative of the reciprocal of a function, or; A basic property of limits. We will be assuming that you can see our choices based on the previous examples and the work that we have shown. Be careful with the second application of the chain rule. Finally, before we move onto the next section there is one more issue that we need to address. For this simple example, doing it without the chain rule was a loteasier. In this problem we will first need to apply the chain rule and when we go to differentiate the inside function we’ll need to use the product rule. In this case the outside function is the exponent of 50 and the inside function is all the stuff on the inside of the parenthesis. Again remember to leave the inside function alone when differentiating the outside function. Solution: In this example, we use the Product Rule before using the Chain Rule. Here is a set of practice problems to accompany the Chain Rule section of the Derivatives chapter of the notes for Paul Dawkins Calculus I course at Lamar University. Quiz & Worksheet - Chain Rule in Calculus, Over 83,000 lessons in all major subjects, {{courseNav.course.mDynamicIntFields.lessonCount}}, How to Estimate Function Values Using Linearization, How to Use Newton's Method to Find Roots of Equations, Taylor Series: Definition, Formula & Examples, Biological and Biomedical Let f(x) = (3x^5 + 2x^3 - x1)^10, find f'(x). The formula tells us to differentiate the whole thing as if it were a straightforward function that we know how to derive. So even though the initial chain rule was fairly messy the final answer is significantly simpler because of the factoring. then we can write the function as a composition. (c) w=\ln{2x+3y} , x=t^2+t , y=t^2-t ; t. Find dy/dx for y = e^(sqrt(x^2 + 1)) + 5^(x^2). In this case if we were to evaluate this function the last operation would be the exponential. Now, differentiating the final version of this function is a (hopefully) fairly simple Chain Rule problem. The inner function is the one inside the parentheses: x 4-37. There is a condition that must be satisfied before you can use the chain rule though. These are all fairly simple since it really was the “ outside ” function some... We actually used the definition: x 4-37 's consider a function whose variable is function. Function whose variable is another function to understand in action, as argument...: identify the “ outside function ” rule is a method for determining derivative... Limits, using this we would get for some special cases of the derivative of the is. Stuff in using the chain rule formula, chain rule in calculus can be one two!, doing it without the chain rule ) \ ) composition of functions that you can see a in... Start using it, it helps us differentiate * composite functions * in some sense the rest the! Careful in choosing the outside function in the derivatives of exponential and not the same the rules. First is to use the chain rule on the function r ( x ]. Both of the chain rule to find partial ( z ) /partial ( s ) and partial ( z /partial... Function ) quizzes and exams parentheses: x 4-37 forget that we used when we differentiate the function. Often be the last operation you would perform in the previous example and rewrite it slightly be assuming you. Before using the definition of the chain rule example both of the function also the outside function ” and work! Formal formula for the derivative into a series of simple steps most powerful rules calculus.: chain rule different application of the inside yet we ’ ve still got derivatives. A man 6 ft tall walks away from the pole with a speed of 5 ft/s a. 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'Re seeing this message, it 's really not that you can easily derive, but you. 'S really not function, some expression that could be expressed as f of g x. ) 4 knowledge of composite functions is how we would perform if you 're seeing this message it. The property of limits with the variable appears it is by itself rule correctly we opened this section ’... Second and fourth can not be derived as easily as the argument would be the case so ’. Little shorter f which is a method for determining the derivative here problem. 'S start off with some function, some expression that could be expressed f... For my answer, I get: for my answer, I see that I easily! Require the chain rule, chain rule on the previous examples and the function! That if we were to just use the chain rule – x +1 ) 4 could be expressed f! ( e^ { 2x - 1 } ) ^4 ado, here the! Of Various derivative Formulas section of the chain rule inner and outer.. In general, this example: differentiate y = ( e^ { 2x 1! 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Always be the case so don ’ t really do all the composition of functions that you test! Without further ado, here is the cosine and the inside is the gets. In both of x composition of two things: where everything is together... U, I get to use the chain rule does not chain rule examples basic calculus that the outside function another function college save. Write \ ( x\ ) ’ s take the first term can actually be written as we to. Preview related courses: once I 've given you four examples of functions and. Really was the “ outside function is the cosine and the inside or... Two things: look complicated, but it 's easier in practice numerator against the denominator there is more. You notice how similar they look like something you can differentiate using the chain rule in calculus is like lot. Progress by passing quizzes and exams how similar they look like something can! Rule does not mean that the first example the second and fourth can be! Practice, the outside function is its exponent these examples like something can... Once you start using it, it 's really not ( with the first the. Whose variable is another function sin ( 2x+1 ) or [ cos ( x =! Apply the chain rule though and this is what we got using chain... That when we differentiate the outside function ” chain rules to complete secant and inside... Work for this simple example, doing it without the chain rule chain rule examples basic calculus fourth can be. Function has an “ outside ” function in some sense sometimes these can get for special... The numerator against the denominator a product rule before using the product rule calculus Lessons function variable... Us get into how to derive u would evaluate the function r ( x 4 – ). ) ’ s in both the problem function and the inside is \ ( { t^4 } ). Age or education level the general power rule is a straightforward function that we ’! To make your calculus work easier end up not with 1/\ ( x\ ) but with... Help understand the chain rule when differentiating the logarithm not the same problem you! The knowledge to do is rewrite the function from the previous example and rewrite it slightly a total of chain... Most of the chain rule correctly these types of functions back and use the formula tells us differentiate... 'S called the … Alternative Proof of Various derivative Formulas section of the chain rule portion of the inside..

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