10x2=66x+28

Solution for 10x2=66x+28 equation:

10x^2=66x+28

We move all terms to the left:

10x^2-(66x+28)=0

We get rid of parentheses

10x^2-66x-28=0

a = 10; b = -66; c = -28;
Δ = b2-4ac
Δ = -662-4·10·(-28)
Δ = 5476
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5476}=74$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-66)-74}{2*10}=\frac{-8}{20}
=-2/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-66)+74}{2*10}=\frac{140}{20}
=7
$