Question

which of the following is not a polynomial identityA) x²+y²=x²+2xy+y²B) x³+y³=(x+y) (x²-xy+y²)C) (x+y)² = x²+2xy+y²D) x²-y²= (x+y) (x-y)

Answer 1

The first option:

A)

x² + y² = x² + 2xy + y²

is not a polynomial identity because the right side of the equation corresponds to a binomial squared, which is given by:

(x + y)² = x² + 2xy + y²

and what you have left side of the given expression is x² + y² and not (x + y)² which is totally different.

Hence, x² + y² = x² + 2xy + y² is not a polynomial identity