how do i factorise
a)9a^2-b^2
b)3x-8y-4xy+6
the first one is a simple case of "difference of squares"
(3a+b)(3a-b)
the second one is the "grouping" type
3x-8y-4xy+6
= 3x + 6 - 4xy - 8y
= 3(x+2) - 4y(x+2)
= (x+2)(3-4y)
a)9a^2-b^2
b)3x-8y-4xy+6
(3a+b)(3a-b)
the second one is the "grouping" type
3x-8y-4xy+6
= 3x + 6 - 4xy - 8y
= 3(x+2) - 4y(x+2)
= (x+2)(3-4y)