Question

Factorise: a^2-b^2-4c^2+4d^2-4(ad-bc)​

Answer 1

Answer:

⇒a^2−b^2−4c^2+4d^2−4(ad−bc)

⇒a^2 −b^2−4c^2+4d^2 −4ad+4bc

⇒(a^2 −4ad+4d^2 )−(b^2 −4bc+4c^2)

∵(x−y)^2=x^2−2xy+y^2

⇒(a−2d)^2−(b−2c)^2

∵x^2−y^2=(x+y)(x−y)

⇒(a−2d+b−2c)(a−2d−b+2c)