Question

(x-y)²-4 (x² - y²) + 4(x + y)²

Answer 1

Answer:

$9y^{2}+x^{2}+6xy$

Step-by-step explanation:

so $(a-b)^{2}=a^{2}-2ab+b^{2}$

therefore

$a=x-y\\b=2(x+y)$

$=(a-b)^{2}\\=[(x-y)-2(x+y)]^{2}\\=(x-y-2x-2y)^{2}\\=(-3y-x)^{2}\\=(-1)^{2}(3y+x)^{2}\\=9y^{2}+x^{2}+6xy$