r^2+2r-33=0 move constant to other side by adding 33 to both sides
r^2+2r=33 halve the linear coefficient, square it and add to both sides, in this case it is just one
r^2+2r+1=34 now the left side is a perfect square...
(r+1)^2=34 take the square root of both sides...
r+1=34^(1/2) subtract 1 from both sides
r=-1+34^(1/2) and -1-34^(1/2)
