(x+9)(2x)=140

Solution for (x+9)(2x)=140 equation:

(x+9)(2x)=140

We move all terms to the left:

(x+9)(2x)-(140)=0

We multiply parentheses

2x^2+18x-140=0

a = 2; b = 18; c = -140;
Δ = b2-4ac
Δ = 182-4·2·(-140)
Δ = 1444
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1444}=38$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-38}{2*2}=\frac{-56}{4}
=-14
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+38}{2*2}=\frac{20}{4}
=5
$