12.25=x^2+9

Solution for 12.25=x^2+9 equation:

12.25=x^2+9

We move all terms to the left:

12.25-(x^2+9)=0

We get rid of parentheses

-x^2-9+12.25=0

We add all the numbers together, and all the variables

-1x^2+3.25=0

a = -1; b = 0; c = +3.25;
Δ = b2-4ac
Δ = 02-4·(-1)·3.25
Δ = 13
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{-(0)-\sqrt{13}}{2*-1}=\frac{0-\sqrt{13}}{-2}
=-\frac{\sqrt{}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{13}}{2*-1}=\frac{0+\sqrt{13}}{-2}
=\frac{\sqrt{}}{-2}
$