Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

Let f (x) be an odd function defined on R with a period T. Then $F(x)=\int_0^xf(t)dt$ is

Options:

periodic with period T

non periodic

periodic with period 2 T

periodic with period T/2

Correct Answer:

periodic with period T

Explanation:

$F (x + T) = F(x) +\int\limits_x^{x+T}f(t)dt$   ..... (i)

Let $g(x)=\int\limits_x^{x+T}f(t)dt$

$g'(x)=f(x+T)-f(x)=0$, ∴ g(x) = constant

But $g(-\frac{T}{2})=\int\limits_{-T/2}^{T/2}f(t)dt=0$     {∵ f(t) is an odd function}

$∴g(x)=g(-\frac{T}{2})=0$; $∴F(x+T)=F(x)$