-30x^2-15x+7=0

Solution for -30x^2-15x+7=0 equation:

-30x^2-15x+7=0

a = -30; b = -15; c = +7;
Δ = b2-4ac
Δ = -152-4·(-30)·7
Δ = 1065
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{-(-15)-\sqrt{1065}}{2*-30}=\frac{15-\sqrt{1065}}{-60}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+\sqrt{1065}}{2*-30}=\frac{15+\sqrt{1065}}{-60}
$