x^2+4-10x-20=-9

Solution for x^2+4-10x-20=-9 equation:

x^2+4-10x-20=-9

We move all terms to the left:

x^2+4-10x-20-(-9)=0

We add all the numbers together, and all the variables

x^2-10x-7=0

a = 1; b = -10; c = -7;
Δ = b2-4ac
Δ = -102-4·1·(-7)
Δ = 128
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:

$\sqrt{\Delta}=\sqrt{128}=\sqrt{64*2}=\sqrt{64}*\sqrt{2}=8\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-8\sqrt{2}}{2*1}=\frac{10-8\sqrt{2}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+8\sqrt{2}}{2*1}=\frac{10+8\sqrt{2}}{2}
$