How do you factorise 3a -12ab?

Answer 1

15

Answer 2

By looking for common factors between the terms, starting with the numbers and then moving onto the letters, and then taking out these common factors.

The common factor of 3 & 12 is 3;

The common factor of a and a is a

There is no common factors with b.

Putting the common factors together results in 3a to take out:

3a x 1 = 3a

3a x -4b = -12ab

Thus 3a - 12ab = 3a(1 - 4b)