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COMEDK · Maths · 28. Indefinite Integration

\(\int \dfrac{d x}{(x+2)\left(x^2+1\right)}=p \log |x+2|+q \log \left|x^2+1\right|+r \tan ^{-1} x+c\) then \(p+q+r=\)

  1. A \(16\)
  2. B \(\dfrac{2}{5}\)
  3. C \(\dfrac{1}{2}\)
  4. D \(\dfrac{7}{10}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\dfrac{1}{2}\)

Step-by-step Solution

Detailed explanation

Let \(\dfrac{1}{(x+2)(x^2+1)} = \dfrac{A}{x+2} + \dfrac{Bx+C}{x^2+1}\). Multiplying both sides by \((x+2)(x^2+1)\), we get \(1 = A(x^2+1) + (Bx+C)(x+2)\). Setting \(x = -2\), we get \(1 = A(4+1) + 0\), which implies \(5A = 1\), so \(A = \dfrac{1}{5}\). Comparing coefficients of…