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# Core 4 help watch

1. Hi,

On a bit of work i've got to do, theres a question mainly based on binomial expansion and the last part of the question i am not sure what to do.

Here is the question:

(a) Find the binomial expansion of (1+x)^(1/3) up to the term in x^2
(b) Show that (8+3x)^(1/3) ≈ 2 + 1/4 x -1/32 x^2 for small values of x
(c) Hence show that ∛9 ≈ 599/288

For part (a) i got 1 + 1/3 x - 1/9 x^2 and for part (b) i got the answer that it required but i haven't got a clue how to do (c)

Any help would be appreciated

Thanks
2. let 8 +3x = 9, then find the value of x and substitute it into ur expansion uve found
3. Put x=1/3 in (b)
4. x^1/3 is the cube root of 3
so subbing a value for x shud give what you are looking for.

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