n(n+5)=60

Solution for n(n+5)=60 equation:

n(n+5)=60

We move all terms to the left:

n(n+5)-(60)=0

We multiply parentheses

n^2+5n-60=0

a = 1; b = 5; c = -60;
Δ = b2-4ac
Δ = 52-4·1·(-60)
Δ = 265
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-\sqrt{265}}{2*1}=\frac{-5-\sqrt{265}}{2}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+\sqrt{265}}{2*1}=\frac{-5+\sqrt{265}}{2}
$