Question 747088
<pre>
Write (a+b+c)<sup>12</sup> as [a+(b+c)]<sup>12</sup>

(a+b+c)<sup>12</sup> = [a+(b+c)]<sup>12</sup> =

Then let d = (b+c)

(a+b+c)<sup>12</sup> = [a+(b+c)]<sup>12</sup> = (a+d)<sup>12</sup>

Use the binomial theorem to expand (a+d)<sup>12</sup>

There will be 13 terms, each term will contain a power of (b+c)
from the 12th power all the way down to the 0th power.

Use the binomial theorem to expand each of those powers of (b+c).

Incidentally there will be a total of 91 terms after all like terms 
are collected.

Edwin</pre>