0=-2(x+9)(x-1)

Solution for 0=-2(x+9)(x-1) equation:

0=-2(x+9)(x-1)

We move all terms to the left:

0-(-2(x+9)(x-1))=0

We add all the numbers together, and all the variables

-(-2(x+9)(x-1))=0

We multiply parentheses ..

-(-2(+x^2-1x+9x-9))=0


We calculate terms in parentheses: -(-2(+x^2-1x+9x-9)), so:

-2(+x^2-1x+9x-9)

We multiply parentheses

-2x^2+2x-18x+18

We add all the numbers together, and all the variables

-2x^2-16x+18

Back to the equation:

-(-2x^2-16x+18)


We get rid of parentheses

2x^2+16x-18=0

a = 2; b = 16; c = -18;
Δ = b2-4ac
Δ = 162-4·2·(-18)
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-20}{2*2}=\frac{-36}{4}
=-9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+20}{2*2}=\frac{4}{4}
=1
$