-30x^2+65x+40=0

Solution for -30x^2+65x+40=0 equation:

-30x^2+65x+40=0

a = -30; b = 65; c = +40;
Δ = b2-4ac
Δ = 652-4·(-30)·40
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{-(65)-95}{2*-30}=\frac{-160}{-60}
=2+2/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(65)+95}{2*-30}=\frac{30}{-60}
=-1/2
$