-15x^2+60x+10=0

Solution for -15x^2+60x+10=0 equation:

-15x^2+60x+10=0

a = -15; b = 60; c = +10;
Δ = b2-4ac
Δ = 602-4·(-15)·10
Δ = 4200
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:

$\sqrt{\Delta}=\sqrt{4200}=\sqrt{100*42}=\sqrt{100}*\sqrt{42}=10\sqrt{42}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(60)-10\sqrt{42}}{2*-15}=\frac{-60-10\sqrt{42}}{-30}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(60)+10\sqrt{42}}{2*-15}=\frac{-60+10\sqrt{42}}{-30}
$