Q. Find the average value of the function f(x)=x−112 from x=2 to x=8. Express your answer as a constant times ln3.Answer: □ln3
Understand the concept: Understand the concept of the average value of a function.The average value of a function f(x) on the interval [a,b] is given by the formula:Average value = (b−a)1∫abf(x)dxHere, a=2, b=8, and f(x)=(x−11)2.
Set up the integral: Set up the integral to find the average value.Average value = (1/(8−2))×∫28(x−11)2dxSimplify the coefficient (1/(8−2)):Average value = (1/6)×∫28(x−11)2dx
Calculate the integral: Calculate the integral.The integral of x−112 with respect to x is 2⋅ln∣x−11∣.So, we need to evaluate this from x=2 to x=8.∫28x−112dx=[2⋅ln∣x−11∣]28
Evaluate at bounds: Evaluate the integral at the bounds and subtract.Plug in the upper bound x=8:2⋅ln∣8−11∣=2⋅ln∣−3∣Since ln∣−3∣=ln(3) (because ln of an absolute value is the same as ln of the positive value), we have:2⋅ln(3)Now plug in the lower bound x=2:2⋅ln∣2−11∣=2⋅ln∣−9∣=2⋅ln(9)Since ln(9)=2⋅ln(3) (because 9 is 2⋅ln∣8−11∣=2⋅ln∣−3∣0), we have:2⋅ln∣8−11∣=2⋅ln∣−3∣1Now subtract the two results:2⋅ln∣8−11∣=2⋅ln∣−3∣2
Multiply by coefficient: Multiply by the coefficient to find the average value.Average value = (61)×(−2×ln(3))Simplify the expression:Average value = −31×ln(3)
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