Question

multiply (3x-y) by (x+y) and verify the result for x = 1 and y = (-2) show me your method of doing​

Answer 1

Answer:

3x²+2xy-y²

Step-by-step explanation:

(3x-y)(x+y) = 3x*x + 3x*y - y*x -y*y

= 3x²+3xy-xy-y²

= 3x²+2xy-y²

verify when x=1 and y = (-2)

(3x-y)(x+y) = 3x²+2xy-y²

{3*1-(-2)}{ 1+(-2)} = 3* 1²+ 2*1*(-2)-(-2)²

(3+2)(-1)= 3 +(-4)-4

5*(-1) = 3-8

-5 = -5

proved....