-5x(x-8)=38

Solution for -5x(x-8)=38 equation:

-5x(x-8)=38

We move all terms to the left:

-5x(x-8)-(38)=0

We multiply parentheses

-5x^2+40x-38=0

a = -5; b = 40; c = -38;
Δ = b2-4ac
Δ = 402-4·(-5)·(-38)
Δ = 840
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{840}=\sqrt{4*210}=\sqrt{4}*\sqrt{210}=2\sqrt{210}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(40)-2\sqrt{210}}{2*-5}=\frac{-40-2\sqrt{210}}{-10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(40)+2\sqrt{210}}{2*-5}=\frac{-40+2\sqrt{210}}{-10}
$