Question

Why Is this algebraic expression is different
(x-y)² = x²-2xy+y²
my question actually is about why x² has an (-) sign and why y² has a (+) sign

Answer 1

Please observe carefully .both x^2 and y^2 are positive in the expansion of (x-y)^2.the product 2xy term is only negative here as the square of a difference of variables is taken.