15=3x^2-2x+3

Solution for 15=3x^2-2x+3 equation:

15=3x^2-2x+3

We move all terms to the left:

15-(3x^2-2x+3)=0

We get rid of parentheses

-3x^2+2x-3+15=0

We add all the numbers together, and all the variables

-3x^2+2x+12=0

a = -3; b = 2; c = +12;
Δ = b2-4ac
Δ = 22-4·(-3)·12
Δ = 148
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:

$\sqrt{\Delta}=\sqrt{148}=\sqrt{4*37}=\sqrt{4}*\sqrt{37}=2\sqrt{37}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-2\sqrt{37}}{2*-3}=\frac{-2-2\sqrt{37}}{-6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+2\sqrt{37}}{2*-3}=\frac{-2+2\sqrt{37}}{-6}
$