Factor the following expressions
x^2-8x+12
3a^3-27a
4y^2-9
x^2-8x+12
can you think of 2 numbers which when multiplied will get you 12 , and when added will get you - 8 ?
3a^3-27a
take out a common factor of 3a, and you are left with an obvious difference of squares
4y^2-9
a very obvious difference of squares