-5x^2+30x+3=0

Solution for -5x^2+30x+3=0 equation:

-5x^2+30x+3=0

a = -5; b = 30; c = +3;
Δ = b2-4ac
Δ = 302-4·(-5)·3
Δ = 960
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:

$\sqrt{\Delta}=\sqrt{960}=\sqrt{64*15}=\sqrt{64}*\sqrt{15}=8\sqrt{15}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-8\sqrt{15}}{2*-5}=\frac{-30-8\sqrt{15}}{-10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+8\sqrt{15}}{2*-5}=\frac{-30+8\sqrt{15}}{-10}
$