Q2.

f(x)=(a+bx)(2-x/16)^9

(a) Find the first 3 terms, in ascending powers of x, of the binomial expansion of

giving each term in its simplest form. I have ended up with the terms 512 -144x+18x^2. (correct)

(4)

, where a and b are constants

Given that the first two terms, in ascending powers of x, in the series expansion of f(x) are

128 and 36x,

(b) find the value of a,

(2)

(c) find the value of b.

(2)

(Total for question = 8 marks)

Apparently to find a, you must form the equation 512a = 128.

I did (a+bx)(512) + 128. I do not understand why you end up with 512a = 128 and not 512a +512bx = 128. Please explain the reasoning

f(x)=(a+bx)(2-x/16)^9

(a) Find the first 3 terms, in ascending powers of x, of the binomial expansion of

giving each term in its simplest form. I have ended up with the terms 512 -144x+18x^2. (correct)

(4)

, where a and b are constants

Given that the first two terms, in ascending powers of x, in the series expansion of f(x) are

128 and 36x,

(b) find the value of a,

(2)

(c) find the value of b.

(2)

(Total for question = 8 marks)

Apparently to find a, you must form the equation 512a = 128.

I did (a+bx)(512) + 128. I do not understand why you end up with 512a = 128 and not 512a +512bx = 128. Please explain the reasoning

(edited 2 months ago)

well nobody can really help you if we don't even know the thing you're expanding

Original post by abuzztheuk

well nobody can really help you if we don't even know the thing you're expanding

my bad hahah

well you're in luck, somehow you got given a 2018 AS maths paper question

[url=AS]https://www.thestudentroom.co.uk/showthread.php?t=5555582]AS Pure Maths May 2018 Question - The Student Room

this will probably help?

[url=AS]https://www.thestudentroom.co.uk/showthread.php?t=5555582]AS Pure Maths May 2018 Question - The Student Room

this will probably help?

(edited 2 months ago)

Original post by abuzztheuk

well you're in luck, somehow you got given a 2018 AS maths paper question

[url=AS]https://www.thestudentroom.co.uk/showthread.php?t=5555582]AS Pure Maths May 2018 Question - The Student Room

[url=AS]https://www.thestudentroom.co.uk/showthread.php?t=5555582]AS Pure Maths May 2018 Question - The Student Room

this will probably help?

i saw the thread.. the steps t makes no sense..

Original post by rishoo1

i saw the thread.. the steps t makes no sense..

Youre multiplying two polynomials and equating to a third so

(a+bx)(2-x/16)^9 = 128 + 36x + ...

Subbing in the first few terms of the binomial gives

(a+bx) (512 -144x+18x^2 + ...) = 128 + 36x + ...

Expand the terms on the left and equate to the right, specifically the constant and linear coefficients.

Original post by mqb2766

Youre multiplying two polynomials and equating to a third so

(a+bx)(2-x/16)^9 = 128 + 36x + ...

Subbing in the first few terms of the binomial gives

(a+bx) (512 -144x+18x^2 + ...) = 128 + 36x + ...

Expand the terms on the left and equate to the right, specifically the constant and linear coefficients.

(a+bx)(2-x/16)^9 = 128 + 36x + ...

Subbing in the first few terms of the binomial gives

(a+bx) (512 -144x+18x^2 + ...) = 128 + 36x + ...

Expand the terms on the left and equate to the right, specifically the constant and linear coefficients.

but when i expand the constant i end uup with 512a +512bx = 128 when i should be ending up with 512a =128?

Original post by rishoo1

but when i expand the constant i end uup with 512a +512bx = 128 when i should be ending up with 512a =128?

If its multiplied by x its not a constant as x is a variable. So equate the constant terms to get a, then equate the linear coefficients (of x) to get b.

Two polynomials are equal (for all values of x) if all their coefficients are equal

(edited 2 months ago)

- A level maths
- A level Maths question
- AS maths help
- How to use Madas Maths
- Maths
- A level maths binomial expansion question HELP
- help with maths a level question - binomial expansion
- Using Binomial Expansion for Large Sums
- Why is this binomial expansion valid for all ranges of x?
- maths help
- Maths question binomial expansion
- math question urgent!!!
- 00
- Maths - binomial expansion
- Expansion
- AS Pure Maths May 2018 Question
- aqa further maths gcse
- Binomial Expansion - a level
- Binomial expansion- Constant term(Question 2
- A-Level maths

- My GYG: Academia Weapon Era ðŸ’ªðŸ˜Œ (ðŸ˜®*ðŸ’¨ðŸ˜)
- [Official thread] Hamas-Israel Conflict
- OCR Alevel English Lit Revision Materials
- Does having excess empathy often blow up in your face?
- How difficult is it
- Sutton Trust US Programme 2024
- S
- Average GCSEs and applying to Russell Group Universities
- Gcse trying to get grade 7,8
- gsce Oxford grades for law
- Official Imperial College 2024 Undergraduate Applicants Thread
- UNIQ 2024 Cohort
- hi
- good romance books?
- My face burns and itches from anything
- Diagnostic Radiography Applicants 2024
- Easter Eggs
- does he like me?
- MPhil Environmental Policy
- Transferring University Past UCAS Deadline

- Hello
- GCU application code
- sad at uni
- Lloyds of London- Business Graduate Scheme
- Motivating myself - my GYG blog :)
- à©ˆâœ©â€§â‚ŠËš year 13 academic comeback
- go big or go home: my guide to conquering gcse's â˜†
- Creating The Future Of Our Dreams - Study23 GYG
- Grade Growth Chronicles | From C's to A's (23-24)
- I want to quit uni so badly but Iâ€™m in too deep
- Last Person to Post an Emoji Here Wins!
- Dilemma between choosing medical or computing science field
- Intermolecular Forces
- How to enjoy uni when living at home?
- How to apply for the University of Manchester (NO UCAS)
- A level revision 2024
- Sciences Po | Admissions 24
- Part time work
- dreading uni
- What To Pack For Uni When First Moving Out

- I got A*AA for my A-Levels - ask me anything.
- 4 A-Levels and an EPQ
- A Level Resit 2023-2024
- UKChO 2024
- Official Year 13 Chat 2023-24
- Official Year 12 Chat 2023-24
- has anyone made a big academic comeback in a levels ? year 13
- Predict your A Level Grades (yr 12 students)
- Spending too long revising to get A*s at A Level
- Bbo 2024

- ABD to AAA in 5 months? ( help Ã°Å¸ËœÂÃ°Å¸ËœÂ )
- maths a level
- I'm failing my a levels and don't know what to do
- Making an academic comeback
- A*A* in maths + further maths A level - ask me anything
- From B/C/D to AAA in 5 months?
- Edexcel IAL biology unit 1 Jan 2024
- Aqa a level biology student made unofficial mark scheme 2023
- Edexcel IAL Maths P1 Jan 2024
- Edexcel A Level Music Paper: Appraising (9MU0/03) - 12th June 2023 [Exam Chat]

- I got A*AA for my A-Levels - ask me anything.
- 4 A-Levels and an EPQ
- A Level Resit 2023-2024
- UKChO 2024
- Official Year 13 Chat 2023-24
- Official Year 12 Chat 2023-24
- has anyone made a big academic comeback in a levels ? year 13
- Predict your A Level Grades (yr 12 students)
- Spending too long revising to get A*s at A Level
- Bbo 2024

- ABD to AAA in 5 months? ( help Ã°Å¸ËœÂÃ°Å¸ËœÂ )
- maths a level
- I'm failing my a levels and don't know what to do
- Making an academic comeback
- A*A* in maths + further maths A level - ask me anything
- From B/C/D to AAA in 5 months?
- Edexcel IAL biology unit 1 Jan 2024
- Aqa a level biology student made unofficial mark scheme 2023
- Edexcel IAL Maths P1 Jan 2024
- Edexcel A Level Music Paper: Appraising (9MU0/03) - 12th June 2023 [Exam Chat]