Factorise

Question 1

15xy + 75y2

Answer 1

15 75
3 5 3 25
5 5

15 = 3 x 5
75 = 3 x 5 x 5

15y(1x + 5y)

Question 2

64x - 40

Answer 2

64                     40
  16        4           10         4
2   8    2  2       2    5    2   2
   2  4
     2  2
60 = 2 x 2 x 2 x 2 x 2 x 2
40 = 2 x 2 x 2 x 5
2 x 2 x 2 = 8                   8(8x - 5)

Question 3

36x^2 - 12x

Answer 3

36 = 2 x 8
8 - 9 x 2
9 - 3 x 3

12 = 3 x 4
4 - 2 x 2

36 = 2 x 2 x 3 x 3
12 = 2 x 2 x 3
2 x 2 x 3 = 12

12x(3x - 1)