2x(5x-8)=8

Solution for 2x(5x-8)=8 equation:

2x(5x-8)=8

We move all terms to the left:

2x(5x-8)-(8)=0

We multiply parentheses

10x^2-16x-8=0

a = 10; b = -16; c = -8;
Δ = b2-4ac
Δ = -162-4·10·(-8)
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-16)-24}{2*10}=\frac{-8}{20}
=-2/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+24}{2*10}=\frac{40}{20}
=2
$