# MathsWatch

#1
Find the positive constants a and b such that x^4 + 9/x^4 = (x^2 - a/(x^2))^2 + b for all non zero values of x.

Damn!!!!! help.
0
2 years ago
#2
(Original post by Dines)
Find the positive constants a and b such that x^4 + 9/x^4 = (x^2 - a/(x^2))^2 + b for all non zero values of x.

Damn!!!!! help.
Is that ?

Expand and compare coefficients.
0
#3
(Original post by Kvothe the arcane)
Is that ?

Expand and compare coefficients.
You there? How to expand. Just give me a starting hint.
1
2 years ago
#4
(Original post by Dines)
You there? How to expand. Just give me a starting hint.
Expand the bracket as you would normally. .
Except in this case, and .
1
2 years ago
#5

(Original post by Dines)
How to expand this
If you know how to expand brackets normally, then this is no different, if not see below
Spoiler:
Show

if it makes it easier say that u=a/x^2
So then you would need to expand (x^2 -y)
Then you can just substitute in the value of u later on
0
2 years ago
#6
(Original post by Kvothe the arcane)
Expand the bracket as you would normally. .
Except in this case, and .
Wouldn't that be
Spoiler:
Show

?
0
2 years ago
#7
(Original post by Kvothe the arcane)
Expand the bracket as you would normally. .
Except in this case, and .
Mu should be a/x^2
0
2 years ago
#8
(Original post by thefatone)
Wouldn't that be
Spoiler:
Show
?
Spoiler:
Show

yes.
0
2 years ago
#9
(Original post by Kvothe the arcane)
Spoiler:
Show

yes.
lol you edit mine aswell xD

guess i should put in a spoiler xD
0
#10
a=3
b=6

Thank you.
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

• University of East Anglia
All Departments Open 13:00-17:00. Find out more about our diverse range of subject areas and career progression in the Arts & Humanities, Social Sciences, Medicine & Health Sciences, and the Sciences. Postgraduate
Wed, 30 Jan '19
• Aston University
Wed, 30 Jan '19
• Solent University
Sat, 2 Feb '19

### Poll

Join the discussion

Remain (1234)
79.61%
Leave (316)
20.39%