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1. (taken from the June 2009 AQA FP3 paper)

Hi, could someone please explain to me the step for the third M1 mark? - where you divide all the terms by 'a'.

I understand that this is what you do, as my teach briefly mentioned it, but I don't know why???? Why do you have to do that step?
2. (Original post by imundercover)
(taken from the June 2009 AQA FP3 paper)

Hi, could someone please explain to me the step for the third M1 mark? - where you divide all the terms by 'a'.

I understand that this is what you do, as my teach briefly mentioned it, but I don't know why???? Why do you have to do that step?
If u try to find the limit without having done the third m1 mark then its pretty hard.

By dividing through a u get only 1 a term which u can clearly see the limit of.

Essentially u are rewriting the term in brackets to find the limit easier.

Hopefully someone else can clarify it further for u.
3. Basically a/(4a+1)=1/(4+1/a) provided a is not 0 (which thankfully for us doesn't change the limit) and so the limits of the two equivalent fractions (equivalent provided a is not 0) is the same. Now the limit of the second fraction is easy because we know 1/a goes to 0 as we let a tend to infinity. So the limit is just 1/(4+0)=1/4. Just divided by a makes the limit more clear and obvious that all.

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