(x+20)(x-4)=2700

Solution for (x+20)(x-4)=2700 equation:

(x+20)(x-4)=2700

We move all terms to the left:

(x+20)(x-4)-(2700)=0

We multiply parentheses ..

(+x^2-4x+20x-80)-2700=0

We get rid of parentheses

x^2-4x+20x-80-2700=0

We add all the numbers together, and all the variables

x^2+16x-2780=0

a = 1; b = 16; c = -2780;
Δ = b2-4ac
Δ = 162-4·1·(-2780)
Δ = 11376
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:

$\sqrt{\Delta}=\sqrt{11376}=\sqrt{144*79}=\sqrt{144}*\sqrt{79}=12\sqrt{79}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-12\sqrt{79}}{2*1}=\frac{-16-12\sqrt{79}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+12\sqrt{79}}{2*1}=\frac{-16+12\sqrt{79}}{2}
$