20x^2-45x-15=0

Solution for 20x^2-45x-15=0 equation:

20x^2-45x-15=0

a = 20; b = -45; c = -15;
Δ = b2-4ac
Δ = -452-4·20·(-15)
Δ = 3225
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:

$\sqrt{\Delta}=\sqrt{3225}=\sqrt{25*129}=\sqrt{25}*\sqrt{129}=5\sqrt{129}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-45)-5\sqrt{129}}{2*20}=\frac{45-5\sqrt{129}}{40}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-45)+5\sqrt{129}}{2*20}=\frac{45+5\sqrt{129}}{40}
$