Question

Simplify. (xy+yz)²-2x²y²z Find the value when x = -1, y = 1 and z = 2. *​

Answer 1

Answer:

          2

(xy+yz)   −2x  2  y  2  z        when x=−1,y=1,z=2

⇒[y(x+z)]  2  −2x  2  y  2  z

⇒y  2 [x  2  +z  2  +2xz−2x  2  z]

⇒(1)  2  [(−1)  2  +2  2  +2(−1)(2)−2(−1)  2  (2)]

⇒[1+4−4−4]⇒−3

∴(xy+yz)  2  −2x  2  y  2  z at x=−1,y=1 and z=2 is −3