X2=-9x+15

Solution for X2=-9x+15 equation:

X2=-9X+15

We move all terms to the left:

X2-(-9X+15)=0

We add all the numbers together, and all the variables

X^2-(-9X+15)=0

We get rid of parentheses

X^2+9X-15=0

a = 1; b = 9; c = -15;
Δ = b2-4ac
Δ = 92-4·1·(-15)
Δ = 141
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{-(9)-\sqrt{141}}{2*1}=\frac{-9-\sqrt{141}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+\sqrt{141}}{2*1}=\frac{-9+\sqrt{141}}{2}
$