4x(6+2x)=80

Solution for 4x(6+2x)=80 equation:

4x(6+2x)=80

We move all terms to the left:

4x(6+2x)-(80)=0

We add all the numbers together, and all the variables

4x(2x+6)-80=0

We multiply parentheses

8x^2+24x-80=0

a = 8; b = 24; c = -80;
Δ = b2-4ac
Δ = 242-4·8·(-80)
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{-(24)-56}{2*8}=\frac{-80}{16}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(24)+56}{2*8}=\frac{32}{16}
=2
$