[" 2.The coetficient of "x'(0<=r<=(n-1))" in the expansion of "],[(x+3)^(n-1)+(x+3)^(n-2)(x+2)+(x+3)^(n-3)(x+2)^(2)+...],[" (a) "^(n)(x+2)^(n-1)," is "],[" (c) "^(n)C_(y)(3'-2^(n))]