x^2-28=5x

Solution for x^2-28=5x equation:

x^2-28=5x

We move all terms to the left:

x^2-28-(5x)=0

a = 1; b = -5; c = -28;
Δ = b2-4ac
Δ = -52-4·1·(-28)
Δ = 137
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-\sqrt{137}}{2*1}=\frac{5-\sqrt{137}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+\sqrt{137}}{2*1}=\frac{5+\sqrt{137}}{2}
$