140=2x(x-4)

Solution for 140=2x(x-4) equation:

140=2x(x-4)

We move all terms to the left:

140-(2x(x-4))=0


We calculate terms in parentheses: -(2x(x-4)), so:

2x(x-4)

We multiply parentheses

2x^2-8x

Back to the equation:

-(2x^2-8x)


We get rid of parentheses

-2x^2+8x+140=0

a = -2; b = 8; c = +140;
Δ = b2-4ac
Δ = 82-4·(-2)·140
Δ = 1184
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:

$\sqrt{\Delta}=\sqrt{1184}=\sqrt{16*74}=\sqrt{16}*\sqrt{74}=4\sqrt{74}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-4\sqrt{74}}{2*-2}=\frac{-8-4\sqrt{74}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+4\sqrt{74}}{2*-2}=\frac{-8+4\sqrt{74}}{-4}
$