(x+2)(2x)=140

Solution for (x+2)(2x)=140 equation:

(x+2)(2x)=140

We move all terms to the left:

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

We multiply parentheses

2x^2+4x-140=0

a = 2; b = 4; c = -140;
Δ = b2-4ac
Δ = 42-4·2·(-140)
Δ = 1136
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:

$\sqrt{\Delta}=\sqrt{1136}=\sqrt{16*71}=\sqrt{16}*\sqrt{71}=4\sqrt{71}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-4\sqrt{71}}{2*2}=\frac{-4-4\sqrt{71}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+4\sqrt{71}}{2*2}=\frac{-4+4\sqrt{71}}{4}
$