9x2+15x=20

Solution for 9x2+15x=20 equation:

9x^2+15x=20

We move all terms to the left:

9x^2+15x-(20)=0

a = 9; b = 15; c = -20;
Δ = b2-4ac
Δ = 152-4·9·(-20)
Δ = 945
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{945}=\sqrt{9*105}=\sqrt{9}*\sqrt{105}=3\sqrt{105}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-3\sqrt{105}}{2*9}=\frac{-15-3\sqrt{105}}{18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+3\sqrt{105}}{2*9}=\frac{-15+3\sqrt{105}}{18}
$