Question

(e) (x - 3y)2 – 2x2 + 18y2 + (x + 3y)2​

Answer 1

Answer:

$(x - 3y)^2 - 2x^2 + 18y^2 + (x + 3y)^2$

Step-by-step explanation:

$(x - 3y)^2 - 2x^2 + 18y^2 + (x + 3y)^2$

$=(x - 3y)^2 + (x + 3y)^2 - 2(x^2 - 9y^2)$

$= (x + 3y)^2 + (x - 3y)^2 - 2(x + 3y)(x - 3y)$  [using the identity $a^2 - b^2 = (a+b)(a-b)$]

$= [(x + 3y) - (x - 3y)]^2$  [using the identity $a^2 - 2ab + b^2 = (a-b)^2$]

$= (6y)^2$

$= 36y^2$