5a(2a+8)=0

Solution for 5a(2a+8)=0 equation:

5a(2a+8)=0

We multiply parentheses

10a^2+40a=0

a = 10; b = 40; c = 0;
Δ = b2-4ac
Δ = 402-4·10·0
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(40)-40}{2*10}=\frac{-80}{20}
=-4
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(40)+40}{2*10}=\frac{0}{20}
=0
$