x2-28x=-12

Solution for x2-28x=-12 equation:

x2-28x=-12

We move all terms to the left:

x2-28x-(-12)=0

We add all the numbers together, and all the variables

x^2-28x+12=0

a = 1; b = -28; c = +12;
Δ = b2-4ac
Δ = -282-4·1·12
Δ = 736
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:

$\sqrt{\Delta}=\sqrt{736}=\sqrt{16*46}=\sqrt{16}*\sqrt{46}=4\sqrt{46}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-28)-4\sqrt{46}}{2*1}=\frac{28-4\sqrt{46}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+4\sqrt{46}}{2*1}=\frac{28+4\sqrt{46}}{2}
$