$\int_{-5}^{5} \log \left(\frac{7-x}{7+x}\right) d x=$

$\int_{-5}^{5} \log \left(\frac{7-x}{7+x}\right) d x=$
  1. 5
  2. 0
  3. -5
  4. 10

Solution

Let $1=\int_{-4}^{5} \log \frac{7-x}{7+x}$ Let $\quad f(x)=\log \frac{7-x}{7+x}$ $f(-x)=\log \left[\frac{7-(-x)}{7+(-x)}\right]=\log \left(\frac{7+x}{7-x}\right)=-\log \left(\frac{7-x}{7+x}\right)=-f(x)$ $\therefore f(x)$ is an odd function $\Rightarrow I=0$

Asked in: MHT CET 2020 (16 Oct Shift 2)

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