Average Function Value — Question 8

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Question 8

Find the average value of the function f(x)=|x|f(x)=|x| on the interval [−2,2][-2,2].

Original worksheet page 1: question and worked solution for 6-1-008
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Question 8 - Solution

The average value of a function on [a,b][a,b] is favg=1b−a∫abf(x)dx.f_{\text{avg}}=\frac{1}{b-a}\int_a^b f(x)\,dx.

Here a=−2a=-2 and b=2b=2, so favg=14∫−22|x|dx.f_{\text{avg}}=\frac{1}{4}\int_{-2}^{2}|x|\,dx.

Since |x||x| is an even function, ∫−22|x|dx=2∫02xdx.\int_{-2}^{2}|x|\,dx = 2\int_{0}^{2}x\,dx.

Evaluate: 2[x22]02=2⋅2=4.2\left[\frac{x^2}{2}\right]_{0}^{2} = 2\cdot 2 = 4.

Compute the average value: favg=14⋅4=1.f_{\text{avg}}=\frac{1}{4}\cdot 4=1.

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Original worksheet page 2: question and worked solution for 6-1-008

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