2X(x+2)=40

Solution for 2X(x+2)=40 equation:

2X(X+2)=40

We move all terms to the left:

2X(X+2)-(40)=0

We multiply parentheses

2X^2+4X-40=0

a = 2; b = 4; c = -40;
Δ = b2-4ac
Δ = 42-4·2·(-40)
Δ = 336
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:

$\sqrt{\Delta}=\sqrt{336}=\sqrt{16*21}=\sqrt{16}*\sqrt{21}=4\sqrt{21}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-4\sqrt{21}}{2*2}=\frac{-4-4\sqrt{21}}{4}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+4\sqrt{21}}{2*2}=\frac{-4+4\sqrt{21}}{4}
$