2x^2-28x=-66

Solution for 2x^2-28x=-66 equation:

2x^2-28x=-66

We move all terms to the left:

2x^2-28x-(-66)=0

We add all the numbers together, and all the variables

2x^2-28x+66=0

a = 2; b = -28; c = +66;
Δ = b2-4ac
Δ = -282-4·2·66
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-28)-16}{2*2}=\frac{12}{4}
=3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+16}{2*2}=\frac{44}{4}
=11
$