72x^2-31x-28=0

Solution for 72x^2-31x-28=0 equation:

72x^2-31x-28=0

a = 72; b = -31; c = -28;
Δ = b2-4ac
Δ = -312-4·72·(-28)
Δ = 9025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9025}=95$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-31)-95}{2*72}=\frac{-64}{144}
=-4/9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-31)+95}{2*72}=\frac{126}{144}
=7/8
$