-15x^2+74x+30=0

Solution for -15x^2+74x+30=0 equation:

-15x^2+74x+30=0

a = -15; b = 74; c = +30;
Δ = b2-4ac
Δ = 742-4·(-15)·30
Δ = 7276
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:

$\sqrt{\Delta}=\sqrt{7276}=\sqrt{4*1819}=\sqrt{4}*\sqrt{1819}=2\sqrt{1819}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(74)-2\sqrt{1819}}{2*-15}=\frac{-74-2\sqrt{1819}}{-30}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(74)+2\sqrt{1819}}{2*-15}=\frac{-74+2\sqrt{1819}}{-30}
$