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TS EAMCET · Maths · Indefinite Integration

If \(\int \frac{x}{(a+x)^5} d x=\frac{1}{k(a+x)^4}(f(x))+c\) then \(\frac{f(-a)}{a k}=\)

  1. A \(\frac{1}{3}\)
  2. B \(\frac{1}{2}\)
  3. C \(\frac{5}{6}\)
  4. D \(\frac{1}{4}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{1}{4}\)

Step-by-step Solution

Detailed explanation

\begin{aligned} & \text { Let } u=x+a \\ & d u=d x \\ & \int \frac{u-a}{u^5} d u=\int \frac{1}{u^4} d u-\int \frac{a}{u^5} d u \\ & =\frac{1}{3 u^3}+\frac{a}{4 u^4}+C=\frac{-4 u+3 a}{12 u^4}+C=\frac{-4(x+a)+3 a}{12(x+a)^4}+C \\ & =\frac{1}{12(x+a)^4}(-4 x-a)+C \\ & f(x)=-4 x-a…