20x2-13x-16=0

Solution for 20x2-13x-16=0 equation:

20x^2-13x-16=0

a = 20; b = -13; c = -16;
Δ = b2-4ac
Δ = -132-4·20·(-16)
Δ = 1449
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:

$\sqrt{\Delta}=\sqrt{1449}=\sqrt{9*161}=\sqrt{9}*\sqrt{161}=3\sqrt{161}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-3\sqrt{161}}{2*20}=\frac{13-3\sqrt{161}}{40}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+3\sqrt{161}}{2*20}=\frac{13+3\sqrt{161}}{40}
$