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

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

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

We move all terms to the left:

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

determiningTheFunctionDomain
(X+6)(X-2)-920=0

We multiply parentheses ..

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

We get rid of parentheses

X^2-2X+6X-12-920=0

We add all the numbers together, and all the variables

X^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}
$