## binomial theorem

1. The problem statement, all variables and given/known data

Find the first four terms in the expansion of $\left(1-3x\right)^{3/2}$. By substituting in a suitable value of x, find an approximation to $97^{1/2}$.

2. Relevant equations

3. The attempt at a solution

I used the binomial expansion formula to work the answer and it is 1- 4.5x - (22x2/8) - (247x3/48) + ... .

Is that correct?

I did the second part and i got 0.848. What do you think?

Thanks in advance for any help.

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Recognitions:
Gold Member
 Quote by naden1 I used the binomial expansion formula to work the answer and it is 1- 4.5x - (22x2/8) - (247x3/48) + ... .
First two terms are correct, it goes wrong after that. Check your calculations again.

Recognitions:
Homework Help
 Quote by naden1 I did the second part and i got 0.848. What do you think?
I think that it's slightly off

## binomial theorem

 Quote by naden1 I did the second part and i got 0.848. What do you think?
The positive square root of 100 is 10, and square root 81 is 9. Where would you expect square root of 97 to lie in?

How did you solve this part?

Recognitions:
Gold Member
 Quote by Mentallic I think that it's a slightly off
Slightly? Wouldn't that be too much?