Question

How do you evaluate `int5` between the interval [0,4]?

Answer 1

I guess it is `int_0^4(5)dx=`
The integral of a constant is equal to the constant times `x`. Once found the anti-derivative, `F(x)`, you evaluate it at the extremes of integration and subtract the values obtained:
`int_a^bf(x)dx=F(b)-F(a)`

In this case `F(x)=5x` and so:
`int_0^4(5)dx=5x|_0^4=(5*4)-(5*0)=20`