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^(7-r)(3/x^2)^r

=c(7,r)(3)^r x^(9-3r)

for that to be a constant the exponent of the x terms must be zero,so

9-3r=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^(9-r)(3/x^2)^r

=c(9,r)(3)^r x^(9-3r)

for that to be a constant the exponent of the x terms must be zero,so

9-3r=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...
- pre-calculus - 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