Posted by Daisy on Monday, January 21, 2008 at 10:00pm.
Find the constant term in the expansion of [x + (3/x squared)]^9
Find the coefficient of (x)^4(y)^9 in the expansion of (x + (2)(y)^3)^7

Calculus  Reiny, Monday, January 21, 2008 at 10:38pm
for the first one, first of all, find the general term.
I got
C(7,r)x^(7r)(3/x^2)^r
=c(7,r)(3)^r x^(93r)
for that to be a constant the exponent of the x terms must be zero,so
93r=0
r=3
so the constant term is C(7,3)(3^3) = 2268
for the second question, to have the x^4, it must be term number 3.
You work this one out, let me know what you got

Calculus  Reiny, Monday, January 21, 2008 at 10:43pm
correction, whenever you see a 7, it should be a 9
so here it is again
for the first one, first of all, find the general term.
I got
C(9,r)x^(9r)(3/x^2)^r
=c(9,r)(3)^r x^(93r)
for that to be a constant the exponent of the x terms must be zero,so
93r=0
r=3
so the constant term is C(9,3)(3^3) = 2268
Answer This Question
Related Questions
 Calculus  Find the coefficient of the x^2 term in the expansion of (3x  (2/x^2...
 binomial expansion help!!!  in the expansion of (1+x)^(n+1) the coefficient of ...
 Math  ç 2x^3 + 3x^2 + x + 1 dx  2x + 1 [2x^3 + 3x^2 + x...
 precalculus  Can you check my answers? 1.Use the Binomial Theorem to expand and...
 binomial expansion  find the term containing y^3 in the expansion of (sqroot 2+...
 algebra  Find the coefficient of the fifth term in the expansion(rootK+3)^8
 Bionomial expansion help agn #thanks  find the third term of the binomial ...
 maths  find the first 3 terms in the expansion of (x+4)(1+3x)^2 as a series in...
 precalculus  Find the designated term of the binomial expansion. 5th term of (...
 Physics  Material X has a coefficient of linear expansion a = 0.00000271/degree...
More Related Questions