Pascal triangle is for powers of binomials. That's a trinomial, so you group it as a binomial.
( (x) + (y+2) )^5.
Now you can use your co-efficients like you would with a binomial. Then you could further simplify the powers of (y+2) that you get similarly with pascal's triangle (if they've asked you to).
Alternatively, Pascal's triangle can be used as a "look-up table" for binomial coefficients, nCr, where nCr is the number of ways of choosing r objects from n. Specifically, nCr is the [r] member of the [n] row(where, here, square brackets signify counting from 0).
If you had the trinomial expansion of ( x + y + z )n then, by picking one term from each bracket in multiplying out, the coefficient of the term
xaybzc (where a+b+c=n)
would be nCa.(n-a)Cb
which is a product of two terms in Pascal's triangle. (It is also given by n!/(a!b!c!) )
more useless info … until the coefficients move to double digits, so for most practical examples (when using it for coefficients), pascal's triangle is also the powers of 11.
11 to the 0 is 1
11 to the 1 is 11
11 to the 2 is 121
1331
etc :)