The factors of $x^2+4 y^2+4 y-4 x y-2 x-8$ are:
Answer & explanation
Correct answer: option 1
= x2+ 4y2 − 4xy + 4y − 2x − 8
= (x−2y)2 + 2(2y−x) − 8
= (x−2y)2 −2(x−2y) − 8
Let A = x−2y
Thus A2 − 2A − 8
= (A−4)(A+2)
Re-substitute the value of A
Thus x2 + 4y2 + 4y − 4xy − 2x − 8= (x−2y−4)(x−2y+2)