You are Here: Home >< Maths

# C4 Binomial Expansion and Partial Fractions watch

1. Hey. I really need some help. Got a tip off that this question was in tomorrows test

Use 2(1+x/8)^1/3 = 2 + x/12 - x²/288, to work out ³√15

Thanks everyone!
2. rewrite 2(1 + x/8)^1/3 as (8 + x)^1/3, let x = 7, and bingo it give you the cube root of 15
3. (Original post by rpotter)
rewrite 2(1 + x/8)^1/3 as (8 + x)^1/3, let x = 7, and bingo it give you the cube root of 15
What if it is non calculator? I think they give you the expansion for a reason?
4. well then express it as fractions, although its not an exact answer just an approximation
5. (Original post by rpotter)
well then express it as fractions, although its not an exact answer just an approximation
??... don't quite understand how you go about that. Can you explain it please. Do you mean put x as 13/2?
6. Just set x=7 in your expansion.
7. (Original post by dvs)
Just set x=7 in your expansion.
ahhhh.. ok thanks

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: November 14, 2005
Today on TSR

### Cambridge interviews

Find out which colleges are sending invitations

### University open days

Wed, 21 Nov '18
• Buckinghamshire New University
Wed, 21 Nov '18
• Heriot-Watt University
Wed, 21 Nov '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams