Question

Show that :
(3xy - 7yz)2 + 84xy2z = (3xy + 7yz)2
​

Answer 1

Answer:

(3xy - 7yz)2 + 84xy2z = (3xy + 7yz)2

using identity

(a- b)^2=a^2 + b^2- 2ab

first expand LHS

((3xy)^2+ (7yz)^2-2(3xy)(7yz)+ 84xy^2z

9x^2y^2+ 49y^2z^2 - 42xy^2z + 84xy^2z

9x^2y^2+ 49y^2z^2 -42xy^2z = LHS

Now, expand RHS

using identity

(a- b)^2=a^2 + b^2- 2ab

(3xy + 7yz)2

((3xy)^2+ (7yz)^2-2(3xy)(7yz)

9x^2y^2+ 49y^2z^2 - 42xy^2z= RHS

LHS = RHS

hence , proved