x(2x+4)-40=350

Solution for x(2x+4)-40=350 equation:

x(2x+4)-40=350

We move all terms to the left:

x(2x+4)-40-(350)=0

We add all the numbers together, and all the variables

x(2x+4)-390=0

We multiply parentheses

2x^2+4x-390=0

a = 2; b = 4; c = -390;
Δ = b2-4ac
Δ = 42-4·2·(-390)
Δ = 3136
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3136}=56$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-56}{2*2}=\frac{-60}{4}
=-15
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+56}{2*2}=\frac{52}{4}
=13
$