-4x^2+9x+40=0

Solution for -4x^2+9x+40=0 equation:

-4x^2+9x+40=0

a = -4; b = 9; c = +40;
Δ = b2-4ac
Δ = 92-4·(-4)·40
Δ = 721
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-\sqrt{721}}{2*-4}=\frac{-9-\sqrt{721}}{-8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+\sqrt{721}}{2*-4}=\frac{-9+\sqrt{721}}{-8}
$