15x=9x^2+4

Solution for 15x=9x^2+4 equation:

15x=9x^2+4

We move all terms to the left:

15x-(9x^2+4)=0

We get rid of parentheses

-9x^2+15x-4=0

a = -9; b = 15; c = -4;
Δ = b2-4ac
Δ = 152-4·(-9)·(-4)
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-9}{2*-9}=\frac{-24}{-18}
=1+1/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+9}{2*-9}=\frac{-6}{-18}
=1/3
$