-10a(a+5)=16

Solution for -10a(a+5)=16 equation:

-10a(a+5)=16

We move all terms to the left:

-10a(a+5)-(16)=0

We multiply parentheses

-10a^2-50a-16=0

a = -10; b = -50; c = -16;
Δ = b2-4ac
Δ = -502-4·(-10)·(-16)
Δ = 1860
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1860}=\sqrt{4*465}=\sqrt{4}*\sqrt{465}=2\sqrt{465}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-50)-2\sqrt{465}}{2*-10}=\frac{50-2\sqrt{465}}{-20}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-50)+2\sqrt{465}}{2*-10}=\frac{50+2\sqrt{465}}{-20}
$