Question

Factorise x2 - 2y + xy - 4
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Answer 1

x²-2y+xy-4

=x²-4+xy-2y

=(x²-2²)+xy-2y by identity x²-y²=(x-y)(x+y)

=(x-2)(x+2) +y(x-2)

=(x-2)(x+2+y)

=(x-2)(x+y+2)