15-3x=5+x2

Solution for 15-3x=5+x2 equation:

15-3x=5+x2

We move all terms to the left:

15-3x-(5+x2)=0

We add all the numbers together, and all the variables

-(+x^2+5)-3x+15=0

We get rid of parentheses

-x^2-3x-5+15=0

We add all the numbers together, and all the variables

-1x^2-3x+10=0

a = -1; b = -3; c = +10;
Δ = b2-4ac
Δ = -32-4·(-1)·10
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-7}{2*-1}=\frac{-4}{-2}
=+2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+7}{2*-1}=\frac{10}{-2}
=-5
$