1.

\(\displaystyle\int_{a+c}^{b+c}f(x)dx = \ ?\)1. \(\displaystyle\int_a^b f(x-c)dx\)2. \(\displaystyle\int_a^b f(x+c)dx\)3. \(\displaystyle\int_a^b f(x)dx\)4. \(\displaystyle\int_{a-c}^{b-c} f(x)dx\)

Answer» Correct Answer - Option 2 : \(\displaystyle\int_a^b f(x+c)dx\)

Explanation:

Given Integral is,

\(I~=~\displaystyle\int_{a+c}^{b+c}\ f(x)dx\)

Put t = x - c i.e. x = t + c

By differentiating we have,

dt = dx

at x = a + c  →  t = a + c - c = a ........(1)

at x = b + c  →  t = b + c -c = b .........(2) 

Now,

\(\displaystyle\int_{a+c}^{b+c}f(x)dx =~\int_a^b f(t+c)dt \)  .........(3)

Also, put t = x then,

t = a →  x = a ,,,,,,from equation (1)

t = b →  x = b ......from equation (2)

From the equation (3)

\(\displaystyle\int_{a+c}^{b+c}f(x)dx =~\int_a^b f(x+c)dt \)

Hence, it is proove.



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