Answer
$\dfrac{25}{4}$
Work Step by Step
We complete the square:
$x^2+5x=x^2+2\cdot \dfrac{5}{2}x=\left(x^2+2\cdot \dfrac{5}{2}x+\left(\dfrac{5}{2}\right)^2\right)-\left(\dfrac{5}{2}\right)^2$
$=\left(x+\dfrac{5}{2}\right)^2-\dfrac{25}{4}$
To complete the square $x^2+5x$, add $\dfrac{25}{4}$.
