8x^2+15x-2=9

Solution for 8x^2+15x-2=9 equation:

8x^2+15x-2=9

We move all terms to the left:

8x^2+15x-2-(9)=0

We add all the numbers together, and all the variables

8x^2+15x-11=0

a = 8; b = 15; c = -11;
Δ = b2-4ac
Δ = 152-4·8·(-11)
Δ = 577
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{577}}{2*8}=\frac{-15-\sqrt{577}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+\sqrt{577}}{2*8}=\frac{-15+\sqrt{577}}{16}
$