15x^2+80=215

Solution for 15x^2+80=215 equation:

15x^2+80=215

We move all terms to the left:

15x^2+80-(215)=0

We add all the numbers together, and all the variables

15x^2-135=0

a = 15; b = 0; c = -135;
Δ = b2-4ac
Δ = 02-4·15·(-135)
Δ = 8100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8100}=90$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-90}{2*15}=\frac{-90}{30}
=-3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+90}{2*15}=\frac{90}{30}
=3
$