(r-9)*(r+3)-(r+9)(r+3) заране спасибо

Question

(r-9)*(r+3)-(r+9)(r+3) заране спасибо

Answer 1

(r-9)×(r+3)-(r+9)(r+3)=(r+3)((r-9)-(r-9))=(r+3)(r-9-r+18)=(r+3)9=9(r+3)