-15x^2+55x-30=0

Solution for -15x^2+55x-30=0 equation:

-15x^2+55x-30=0

a = -15; b = 55; c = -30;
Δ = b2-4ac
Δ = 552-4·(-15)·(-30)
Δ = 1225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1225}=35$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(55)-35}{2*-15}=\frac{-90}{-30}
=+3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(55)+35}{2*-15}=\frac{-20}{-30}
=2/3
$