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

I guess it is ${\int}_{0}^{4} \left(5\right) \mathrm{dx} =$
The integral of a constant is equal to the constant times $x$. Once found the anti-derivative, $F \left(x\right)$, you evaluate it at the extremes of integration and subtract the values obtained:
${\int}_{a}^{b} f \left(x\right) \mathrm{dx} = F \left(b\right) - F \left(a\right)$
In this case $F \left(x\right) = 5 x$ and so:
${\int}_{0}^{4} \left(5\right) \mathrm{dx} = 5 x {|}_{0}^{4} = \left(5 \cdot 4\right) - \left(5 \cdot 0\right) = 20$