9^2+r^2=(3+r)(3+r)

Solution for 9^2+r^2=(3+r)(3+r) equation:

9^2+r^2=(3+r)(3+r)

We move all terms to the left:

9^2+r^2-((3+r)(3+r))=0

We add all the numbers together, and all the variables

r^2-((r+3)(r+3))+9^2=0

We add all the numbers together, and all the variables

r^2-((r+3)(r+3))+81=0

We multiply parentheses ..

r^2-((+r^2+3r+3r+9))+81=0


We calculate terms in parentheses: -((+r^2+3r+3r+9)), so:

(+r^2+3r+3r+9)

We get rid of parentheses

r^2+3r+3r+9

We add all the numbers together, and all the variables

r^2+6r+9

Back to the equation:

-(r^2+6r+9)


We get rid of parentheses

r^2-r^2-6r-9+81=0

We add all the numbers together, and all the variables

-6r+72=0

We move all terms containing r to the left, all other terms to the right

-6r=-72

r=-72/-6

r=+12