9(20)=(x+6)(x-2)

Solution for 9(20)=(x+6)(x-2) equation:

9(20)=(x+6)(x-2)

We move all terms to the left:

9(20)-((x+6)(x-2))=0

We multiply parentheses ..

-((+x^2-2x+6x-12))+920=0


We calculate terms in parentheses: -((+x^2-2x+6x-12)), so:

(+x^2-2x+6x-12)

We get rid of parentheses

x^2-2x+6x-12

We add all the numbers together, and all the variables

x^2+4x-12

Back to the equation:

-(x^2+4x-12)


We get rid of parentheses

-x^2-4x+12+920=0

We add all the numbers together, and all the variables

-1x^2-4x+932=0

a = -1; b = -4; c = +932;
Δ = b2-4ac
Δ = -42-4·(-1)·932
Δ = 3744
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:

$\sqrt{\Delta}=\sqrt{3744}=\sqrt{144*26}=\sqrt{144}*\sqrt{26}=12\sqrt{26}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-12\sqrt{26}}{2*-1}=\frac{4-12\sqrt{26}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+12\sqrt{26}}{2*-1}=\frac{4+12\sqrt{26}}{-2}
$