Question

a$9(x+y)^{2} - 16(x-2y)^{2}$

Answer 1

Answer:

$82xy-7x^2-7y^2$

Step-by-step explanation:

using the algebric identity,

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

Therefore,

$9(x+y)^2-16(x-2y)^2=9(x^2+2xy+y^2)-16(x^2-4xy+y^2)\\\\ =9x^2+18xy+9y^2-16x^2+64xy-16y^2\\=9x^2-16x^2+18xy+64xy+9y^2-16y^2\\=-7x^2+82xy-7y^2=82xy-7x^2-7y^2-ANS$

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