4x(2x+10)=0

Solution for 4x(2x+10)=0 equation:

4x(2x+10)=0

We multiply parentheses

8x^2+40x=0

a = 8; b = 40; c = 0;
Δ = b2-4ac
Δ = 402-4·8·0
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(40)-40}{2*8}=\frac{-80}{16}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(40)+40}{2*8}=\frac{0}{16}
=0
$