-15x2+28x-5=0

Solution for -15x2+28x-5=0 equation:

-15x^2+28x-5=0

a = -15; b = 28; c = -5;
Δ = b2-4ac
Δ = 282-4·(-15)·(-5)
Δ = 484
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{484}=22$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-22}{2*-15}=\frac{-50}{-30}
=1+2/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+22}{2*-15}=\frac{-6}{-30}
=1/5
$