# Binomial expansion question hard surds core 1Watch

#1
This is a core 1 binomial expansion question for mei:

given that (√3-√2)^5 = a√3 - b√2 evaluate a and b

0

#2
someone told me a is 89 and b is -109 but i have no clue how they got there??? could anyone help me to figure out how to solve??
0
4 years ago
#3
you can use Pascal's triangle to help with this:
so because it's to the power of 5 you use the numbers ~ 1, 5, 10, 10, 5, 1
so then you create the equation:

1(√ 3)^0(-√ 2)^5 + 5(√ 3)^1(-√ 2)^4 + 10(√ 3)^2(-√ 2)^3 + 10(√ 3)^3(-√ 2)^2 + 5(√ 3)^4(-√ 2)^1 +1(√ 3)^5(-√ 2)^0
= -5.657 + 34.64 -60√ 2 +60√ 3 -63.64 + 15.59

then you look for the 2 components that have √ 2 and √ 3 ; they are A&b,
however i got a= -60 & b= 60 not 89 and -109

this is what i was taught so don't take my word for it
0
X

new posts
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• Cranfield University
Cranfield Forensic MSc Programme Open Day Postgraduate
Thu, 25 Apr '19
• University of the Arts London
Open day: MA Footwear and MA Fashion Artefact Postgraduate
Thu, 25 Apr '19
• Cardiff Metropolitan University
Sat, 27 Apr '19

### Poll

Join the discussion

#### Have you registered to vote?

Yes! (255)
38.93%
No - but I will (45)
6.87%
No - I don't want to (47)
7.18%
No - I can't vote (<18, not in UK, etc) (308)
47.02%