-9c(c-4)=-(c+20)

Solution for -9c(c-4)=-(c+20) equation:

-9c(c-4)=-(c+20)

We move all terms to the left:

-9c(c-4)-(-(c+20))=0

We multiply parentheses

-9c^2+36c-(-(c+20))=0


We calculate terms in parentheses: -(-(c+20)), so:

-(c+20)

We get rid of parentheses

-c-20

We add all the numbers together, and all the variables

-1c-20

Back to the equation:

-(-1c-20)


We get rid of parentheses

-9c^2+36c+1c+20=0

We add all the numbers together, and all the variables

-9c^2+37c+20=0

a = -9; b = 37; c = +20;
Δ = b2-4ac
Δ = 372-4·(-9)·20
Δ = 2089
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(37)-\sqrt{2089}}{2*-9}=\frac{-37-\sqrt{2089}}{-18}
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(37)+\sqrt{2089}}{2*-9}=\frac{-37+\sqrt{2089}}{-18}
$