## Elementary Algebra

RECALL: $(a-b)^2 = a^2-2ab+b^2$ Note that $(-x+y) = -(x-y)$ Thus, $(-x+y)(x-y) = -(x-y)(x-y) = -(x-y)^2$ Use the formula above to obtain: $-(x-y)^2 \\= -(x^2-2xy+y^2) \\= -x^2-(-2xy)-y^2 \\=-x^2+2xy-y^2$ Therefore, the given statement is false.