binomial

1. Find the total number of terms in the expansion of (x + y + z + w)ⁿ, n âˆˆ N.

2. Find numerically greatest term in the expansion of (2 + 3x)⁹, when x = 3/2

4 Answers

i think we can solve the first problem like this

x^r1y^r2z^r3w^r4 will be at term if

r1+r2+r3+r4 =n

so we need to find the number of sets (r1 ,r2 ,r3 ,r4 ;integral set o'course)

that satisfies the above condition :

this is equal to ⁿ⁺³C_n=(n+3)(n+2)(n+1)6

explain q1

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