7(x)=x^2+0x-9

Solution for 7(x)=x^2+0x-9 equation:

7(x)=x^2+0x-9

We move all terms to the left:

7(x)-(x^2+0x-9)=0

We get rid of parentheses

-x^2+7x-0x+9=0

We add all the numbers together, and all the variables

-1x^2+6x+9=0

a = -1; b = 6; c = +9;
Δ = b2-4ac
Δ = 62-4·(-1)·9
Δ = 72
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:

$\sqrt{\Delta}=\sqrt{72}=\sqrt{36*2}=\sqrt{36}*\sqrt{2}=6\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-6\sqrt{2}}{2*-1}=\frac{-6-6\sqrt{2}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+6\sqrt{2}}{2*-1}=\frac{-6+6\sqrt{2}}{-2}
$