Question 106708
Unfortunately, this problem isn't that simple


Remember {{{(3r-2s)^4=(3r-2s)(3r-2s)(3r-2s)(3r-2s)}}}



So this means you have to foil the first two products and the last two to get



{{{(3r-2s)(3r-2s)(3r-2s)(3r-2s)=(9r^2-12rs+4s^2)(9r^2-12rs+4s^2)}}}



Now break up {{{(9r^2-12rs+4s^2)(9r^2-12rs+4s^2)}}} to get



{{{9r^2(9r^2-12rs+4s^2)-12rs(9r^2-12rs+4s^2)+4s^2(9r^2-12rs+4s^2)}}}



Now distribute


{{{81r^4-108r^3s+36r^2s^2-108r^3s+144r^2s^2-48rs^3+36r^2s^2-48rs^3+16s^4}}}




Combine like terms


{{{81r^4-216r^3s+216r^2s^2-96rs^3+16s^4}}}



So {{{(3r-2s)^4=81r^4-216r^3s+216r^2s^2-96rs^3+16s^4}}}