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TS EAMCET · Maths · Definite Integration

If \(f\) is defined on \(\mathbb{R}\) such that \(f(\mathrm{x}) f(-\mathrm{x})=9\), then \(\int_{-23}^{23} \frac{d x}{3+f(x)}\)

  1. A \(\frac {51}{3}\)
  2. B \(\frac {49}{3}\)
  3. C \(\frac {46}{3}\)
  4. D \(\frac {46}{6}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac {46}{6}\)

Step-by-step Solution

Detailed explanation

\begin{aligned} & f(x) \cdot f(-x)=9 \\ & I=\int_{-23}^{23} \frac{d x}{3+f(x)}... (i) \\ & I=\int_{-23}^{23} \frac{d x}{3+f(-x)} \quad(f(a+b-x) \text { property }) \\ & I=\int_{-23}^{23} \frac{d x}{3+\frac{9}{f(x)}}=\int_{-23}^{23} \frac{f(x) d x}{3(f(x)+3)}... (ii) \\ & \text {…