x(2x-4)=70

Solution for x(2x-4)=70 equation:

x(2x-4)=70

We move all terms to the left:

x(2x-4)-(70)=0

We multiply parentheses

2x^2-4x-70=0

a = 2; b = -4; c = -70;
Δ = b2-4ac
Δ = -42-4·2·(-70)
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{-(-4)-24}{2*2}=\frac{-20}{4}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+24}{2*2}=\frac{28}{4}
=7
$