Which sum or difference is modeled by the algebra tiles? a. (-x2 2x 3) − (x2 − 2x − 1) = -2x2 2 b. (-x2 2x 3) − (-x2 2x 1) = -2x2 2 c. (-x2 2x 3) (-x2 2x 1) = -2x2 2 d. (-x2 2x 3) (-x2 − 2x − 1) = -2x2 2