Multiple choice Factorized form of r2 – 10r + 21 is (r -1) (r -4) (r -7) (r – 3) (r -7) (r +3) (r+7) (r +3) Reveal answer Fill a bubble to check yourself B Correct answer Explanation r2 – 10 r + 21 = r2 -7 r – 3r + 21 = (r-7 ) (r-3)