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# Binomial Help. :D watch

1. Hi,

I have to expand (1+x/8)^1/2 in ascending powers of x up to and including the term in x^2.

Then hence by writing x = 1 in the expansion, show that root2 is approx 256/181.

For the expansion I got:-

1 + x/16 - (x^2)/512 +... I think thats correct.

For the approximation I cant get the fraction required.

(1 + 1/8)^1/2 = 543/512

therefore

sqroot(9/8) = 543/512

3root2/4 = 543/512

therefore I get root2 = 181/128 which is not the correct fraction. Can someone help me out please.
2. (Original post by FutureMedic)
Hi,

I have to expand (1+x/8)^1/2 in ascending powers of x up to and including the term in x^2.

Then hence by writing x = 1 in the expansion, show that root2 is approx 256/181.

For the expansion I got:-

1 + x/16 - (x^2)/512 +... I think thats correct.

For the approximation I cant get the fraction required.

(1 + 1/8)^1/2 = 543/512

therefore

sqroot(9/8) = 543/512

3root2/4 = 543/512

therefore I get root2 = 181/128 which is not the correct fraction. Can someone help me out please.
Nvm, I see where I have gone wrong. :L

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