# How do you factor #4x - x^2 - 4y + xy# completely?

##### 1 Answer

Oct 7, 2016

#### Explanation:

Factorise by

#color(blue)"grouping the terms"# as follows.

#[4x-x^2]+[-4y+xy]# now factorise each group.

#rArrcolor(red)(x)color(blue)((4-x))color(red)(-y)color(blue)((4-x))# We now have a common factor of (4 - x).

#rArrcolor(blue)((4-x))color(red)((x-y))#

#rArr4x-x^2-4y+xy=(4-x)(x-y)#