20x^2-15x-25=0

Solution for 20x^2-15x-25=0 equation:

20x^2-15x-25=0

a = 20; b = -15; c = -25;
Δ = b2-4ac
Δ = -152-4·20·(-25)
Δ = 2225
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:

$\sqrt{\Delta}=\sqrt{2225}=\sqrt{25*89}=\sqrt{25}*\sqrt{89}=5\sqrt{89}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-5\sqrt{89}}{2*20}=\frac{15-5\sqrt{89}}{40}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+5\sqrt{89}}{2*20}=\frac{15+5\sqrt{89}}{40}
$