Question

multiply (3x-y) by (x+y) and verify the results for x=1 and y=(-2)​

Answer 1

$(3x - y) \times (x + y) \\ = (3(1) - ( - 2) )\times ((1) + ( - 2)) \\ = (3 + 2) \times (1 - 2) \\ = 5 \times - 1 \\ = - 5$