
Nataliya D. answered 03/20/13
Patient and effective tutor for your most difficult subject.
I like answers above, but want to give another approach, this is algebra any way.
(2r + 1)(r - 2) = - (3r - 6)
(2r + 1)(r - 2) + (3r - 6) = 0
(2r + 1)(r - 2) + 3(r - 2) = 0 , factor out (r - 2)
(r - 2)(2r + 1 + 3) = 0
(r - 2)(2r + 4) = 0 , factor out 2
2(r - 2)(r + 2) = 0
Product equal zero if at least one factor equal zero.
r1,2 = ±2