4x^2-13x=66

Solution for 4x^2-13x=66 equation:

4x^2-13x=66

We move all terms to the left:

4x^2-13x-(66)=0

a = 4; b = -13; c = -66;
Δ = b2-4ac
Δ = -132-4·4·(-66)
Δ = 1225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1225}=35$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-35}{2*4}=\frac{-22}{8}
=-2+3/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+35}{2*4}=\frac{48}{8}
=6
$