Posted by **gandhish** on Monday, March 18, 2013 at 12:32pm.

find the coefficient of x^29 in the expansion (1+2x)^12 .(1+x)^18

- math -
**Steve**, Monday, March 18, 2013 at 1:38pm
(2x+1)^12

= (2x)^12 + 12(2x)^11 + ...

= 2^12 x^12 + 12*2^11 x^11 + ...

(x+1)^18 = x^18 + 18x^17 + 9*17 x^16 + ...

= 2^12 x^30 + (18*2^12 + 12)x^29 + ...

so, 18*2^12 + 12 = 73740

- math -
**Steve**, Monday, March 18, 2013 at 1:45pm
(2x+1)^12 = 2^12 x^12 + 12*2^11 x^11 + ...

(x+1)^18 = x^18 + 18x^17 + ...

multiply the two expansions to get

2^12 x^30 + (18*2^12 + 12*2^11) x^29 + ...

so, we have 18*2^12 + 12*2^11 = 98304

## Answer this Question

## Related Questions

- Calculus - Find the constant term in the expansion of [x + (3/x squared)]^9 Find...
- Physics - In my lab of linear expansion, I need to find out the coefficient of ...
- physics - The coefficient of apparent expansion of a liquid when determined ...
- Binomal Theorem - 1A> What is the coefficient of x^(2r) in the expansion of (...
- MATH - find the coefficient of x^5 in the expansion (x+2)(x+1)^8
- math - Find the coefficient of x³ in the expansion of (2x+5)^6
- Math - Find the coefficient of x^2y^3 in the binomial expansion of (x-2y)^5.
- maths - The coefficient of x^2 is 69 in the expansion of (1-ax)^24, where a>0...
- Math - Find the numerical value of the coefficient x^11 in the expansion of (x^2...
- Physics - A 3.00-liter aluminum cylinder at 5.00°C is filled to the brim with ...

More Related Questions