X(2x+6)=80

Solution for X(2x+6)=80 equation:

X(2X+6)=80

We move all terms to the left:

X(2X+6)-(80)=0

We multiply parentheses

2X^2+6X-80=0

a = 2; b = 6; c = -80;
Δ = b2-4ac
Δ = 62-4·2·(-80)
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-26}{2*2}=\frac{-32}{4}
=-8
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+26}{2*2}=\frac{20}{4}
=5
$