2x^2+15x-168.75=0

Solution for 2x^2+15x-168.75=0 equation:

2x^2+15x-168.75=0

a = 2; b = 15; c = -168.75;
Δ = b2-4ac
Δ = 152-4·2·(-168.75)
Δ = 1575
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:

$\sqrt{\Delta}=\sqrt{1575}=\sqrt{225*7}=\sqrt{225}*\sqrt{7}=15\sqrt{7}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-15\sqrt{7}}{2*2}=\frac{-15-15\sqrt{7}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+15\sqrt{7}}{2*2}=\frac{-15+15\sqrt{7}}{4}
$