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17calculus > derivatives > quotient rule |
Topics You Need To Understand For This Page
Some of the practice problems require you to know the following rules also (in their basic form, not including the chain rule). If you don't know one or more of these rules, no worries. You can filter them from the list of practice problems. |
You do NOT need to know the chain rule for anything on this page, including practice problems. For practice problems using the quotient rule and chain rule, see the chain rule page. |
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Quotient Rule |
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When you are first learning the quotient rule, it is a good idea to write out intermediate steps. This rule is easy to get confused about, so writing out intermediate steps will help you get your head around the details. Later, you will be able to do more in your head and less on paper. |
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The quotient rule looks like this. If you have a function \(\displaystyle{f(x) = \frac{n(x)}{d(x)}} \), the quotient rule says the derivative is \(\displaystyle{ f'(x) = \frac{d \cdot n' - n \cdot d'}{d^2} }\). In this equation, we have used \(n(x)\) to denote the expression in the numerator and \(d(x)\) to denote the expression in the denominator.
Okay, so this seems pretty straight-forward. Let's do an example. Try this on your own before looking at the solution.
Calculate the derivative of \( \displaystyle{f(x) = \frac{x+5}{x^2}} \). | |
A Note About Simplifying | |
Things To Watch For |
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There are a few things we see students do quite often that we want to warn you about.
- First, go back to the example and notice that we take the denominator and assign it directly to d(x). I have seen students think \( d(x) = x^{-2} \). This is NOT the case. We do not take the denominator, move it to the numerator and call that d(x). So be very careful here.
- Second, again, go back to the example and notice that, when simplifying, the first thing we do in the numerator is look for a common factor between the two terms. In the example, we had a factor of x. We factored it out and canceled it with an x in the denominator. This happens quite often when using the quotient rule.
- Third, the quotient rule itself is not that difficult to do. The thing that will probably trip you up the most is the algebra you have to do with simplifying. So this technique will often challenge you to remember and use your algebra rules related to factoring and powers.
Before working some practice problems, take a few minutes and watch this video showing a proof of the quotient rule.
MIP4U - Proof of the Quotient Rule | |
Okay, it is time for some practice problems. After that, the chain rule is next. |
chain rule → |
Search 17Calculus
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use basic derivatives and quotient rule only | ||||
use trig rules | ||||
use exponential and/or logarithmic rules | ||||
Practice Problems |
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Instructions - - Unless otherwise instructed, calculate the derivatives of the following functions using the quotient rule, giving your answers in simplified form.
Level A - Basic |
Practice A05 | |
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\(\displaystyle{f(x)=\frac{7x^2+1}{e^x}}\) | |
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solution |
Practice A06 | |
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\(\displaystyle{y=\frac{t^2+2}{t^4-3t^2+1}}\) | |
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solution |
Practice A07 | |
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\(\displaystyle{f(x)=\frac{x-1}{x^2+2x+1}}\) | |
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solution |
Practice A08 | |
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\(\displaystyle{f(x)=\frac{1}{x+1}-\frac{1}{x-1}}\) | |
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solution |
Practice A09 | |
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\(\displaystyle{f(x)=\frac{x+1}{x-1}}\) | |
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solution |
Practice A10 | |
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\(\displaystyle{f(x)=\frac{x^2-4}{x^2+4}}\) | |
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solution |
Practice A11 | |
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\(\displaystyle{f(x)=\frac{3}{x^2+x+1}}\) | |
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solution |
Practice A12 | |
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\(\displaystyle{y=\frac{45}{5+x+\sqrt{x}}}\) | |
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solution |
Practice A13 | |
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\(\displaystyle{y=\frac{x^2+1}{x^5+x}}\) | |
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solution |
Practice A14 | |
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\(\displaystyle{y=\frac{\tan(x)}{x^{3/2}+5x}}\) | |
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solution |
Practice A15 | |
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\(\displaystyle{f(x)=\frac{x^2+3x}{x+4}}\) | |
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solution |
Level B - Intermediate |
Practice B01 | |
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\(\displaystyle{f(x)=\frac{x}{x+c/x}}\) | |
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solution |
