-10s(s+2)=-71

Solution for -10s(s+2)=-71 equation:

-10s(s+2)=-71

We move all terms to the left:

-10s(s+2)-(-71)=0

We add all the numbers together, and all the variables

-10s(s+2)+71=0

We multiply parentheses

-10s^2-20s+71=0

a = -10; b = -20; c = +71;
Δ = b2-4ac
Δ = -202-4·(-10)·71
Δ = 3240
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{3240}=\sqrt{324*10}=\sqrt{324}*\sqrt{10}=18\sqrt{10}$
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-18\sqrt{10}}{2*-10}=\frac{20-18\sqrt{10}}{-20}
$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+18\sqrt{10}}{2*-10}=\frac{20+18\sqrt{10}}{-20}
$