How do you factor #(A-B)^3 - B^3#?

Question

1655 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-05-31T13:16:09

This is a difference of cubes, so we can use the identity:

#P^3-Q^3 = (P-Q)(P^2+PQ+Q^2)# ....

#(A-B)^3 - B^3#

#=((A-B)-B)((A-B)^2+(A-B)B +B^2)#

#=(A-2B)(A^2-2AB+B^2+AB-B^2+B^2)#

#=(A-2B)(A^2-AB+B^2)#

This has no simpler factors with real coefficients.