(x)=x(2)-8x+15

Solution for (x)=x(2)-8x+15 equation:

(x)=x(2)-8x+15

We move all terms to the left:

(x)-(x(2)-8x+15)=0

We add all the numbers together, and all the variables

-(+x^2-8x+15)+x=0

We get rid of parentheses

-x^2+8x+x-15=0

We add all the numbers together, and all the variables

-1x^2+9x-15=0

a = -1; b = 9; c = -15;
Δ = b2-4ac
Δ = 92-4·(-1)·(-15)
Δ = 21
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{21}}{2*-1}=\frac{-9-\sqrt{21}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+\sqrt{21}}{2*-1}=\frac{-9+\sqrt{21}}{-2}
$