kill(all)$

van=facebook.com/LearningCalculus$

f(x):=x^2+3;

'integrate(f(x),x)=integrate(f(x),x)+C;

F(x,C):=''(integrate(f(x),x)+C)$ F(x,C);

integrate(f(x),x,-1,5);

      The derivative of a constant is zero.

diff(integrate(f(x),x,-1,5),x);

[-1,f(-1)];
[ 5,f( 5)];

[-1,F(-1,C)];
[ 5,F( 5,C)];