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NDA 2021
Exam
NDA
Year
2021
Subject
Mathematics
Chapter
Definite Integration

NDA 2021 · Mathematics · Definite Integration

If ∫_0^a[f(x)+f(-x)] d x=∫_ -a ^a g(x) d x then what is g(x) equal...

If ∫0a[f(x)+f(−x)]dx=∫−aag(x)dx\int_0^a[f(x)+f(-x)] d x=\int_{-a}^a g(x) d x then what is g(x)g(x) equal to?

Options

  1. Af(x)f(x)
  2. Bf(−x)+f(x)f(-x)+f(x)
  3. C−f(x)-f(x)
  4. DNone of the above

Correct answer

A. f(x)f(x)

Step-by-step solution

∫0a[f(x)+f(−x)]⋅dx=∫−aag(x)⋅dx\int_0^a[f(x)+f(-x)] \cdot d x=\int_{-a}^a g(x) \cdot d x=∫−a0g(x)⋅dx+∫0ag(x)⋅dx=∫0ag(−x)⋅dx+∫0ag(x)⋅dx\begin{aligned} & =\int_{-a}^0 g(x) \cdot d x+\int_0^a g(x) \cdot d x \\ & =\int_0^a g(-x) \cdot d x+\int_0^a g(x) \cdot d x\end{aligned}=∫0a[g(x)+g(−x)]⋅dx∴f(x)=g(x)=\int_0^a[g(x)+g(-x)] \cdot d x\therefore f(x)=g(x)
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