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# C2 watch

1. Hey guys, now im rather confused with this question because there are so many different methods:

(1+3x)^4..there's the combination way, binomial etc, either way i am getting different answers each time which don't make sense. Anyone care to do this?

Cheers rather easy i know
2. What answer do you get?

I'm getting;

81x^4 + 108x³ + 54x² + 12x + 1
3. (r+1)^th term = nCr.1^(n-r).(3x)^r
Applying this,
1+12x+54x^2+108x^3+81x^4
4. (Original post by gemma.....)
Hey guys, now im rather confused with this question because there are so many different methods:

(1+3x)^4..there's the combination way, binomial etc, either way i am getting different answers each time which don't make sense. Anyone care to do this?

Cheers rather easy i know
Coefficients are
1,4,6,4,1,

(1+3x)^4
= 1*1^4*(3x)^0 + 4*1^3*(3x)^1 + 6*1^2*(3x)^2 + 4*1^1*(3x)^3 + 1*1^0*(3x)^4

= 1 + 12x + 54x^2 + 108x^3 + 81x^4
5. cheers guys i actually did get that i lack confidence and for some reason i had this stupid thought that all the numbers had to increase so i thought 81 looked wrong - crazy!

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