Find the average value of the function f(x)=6−x4 from x=7 to x=9. Write your answer as the logarithm of a single number in simplest form.Answer: ln(□)
Q. Find the average value of the function f(x)=6−x4 from x=7 to x=9. Write your answer as the logarithm of a single number in simplest form.Answer: ln(□)
Set Up Integral: The average value of a continuous function f(x) on the interval [a,b] is given by the formula:Average value = (1/(b−a))⋅∫abf(x)dxHere, a=7, b=9, and f(x)=(4)/(6−x).First, we need to set up the integral to find the average value.
Calculate Integral: Now we calculate the integral of f(x) from x=7 to x=9. ∫796−x4dxTo integrate this function, we can use a substitution method. Let u=6−x, then du=−dx.
Substitution Method: Substituting u into the integral, we get:∫796−x4dx=−∫−1−3u4duNotice that the limits of integration have also changed according to the substitution u=6−x. When x=7, u=−1, and when x=9, u=−3.
Evaluate Integral: Now we integrate u4 with respect to u:∫u4du=4⋅ln∣u∣ Evaluating this from −1 to −3 gives us:4⋅ln∣−3∣−4⋅ln∣−1∣
Simplify Expression: Since ln∣−1∣=ln(1)=0, the expression simplifies to:4×ln∣−3∣−4×0=4×ln(3)
Find Average Value: Now we need to divide this result by (b−a) to find the average value:Average value = (9−7)1×4×ln(3)=21×4×ln(3)=2×ln(3)
Final Result: The average value of the function f(x) from x=7 to x=9 is therefore 2⋅ln(3). This is the logarithm of a single number, as required.
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