The integral expression is .

Consider .

Assume .

Apply derivative on each side.

. 

Change of integral limits :

Lower limit: If then .

Upper limit: If then .

Substitute , and change of limits in .

.

Replace the variable with .

.

Hence it is verified.

.

Prove the above expression, graphically by considering the example function .

Consider the lower and upper limits as and .

Consider the constant as .

.

Here we need to prove,.

Graphically the areas of the regions under the curve are same and the value is  .

.