Cambridge Prelim MX1 Textbook Marathon/Q&A (2 Viewers)

Usernameismyname

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Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread

Hey

It'll be greatly appreciated if someone could help me out with question 22 of Exercise 4J.

Thanks
 

Blitz_N7

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Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread


Unsure on how to do this question :/
 

integral95

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Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread


Unsure on how to do this question :/
a) it's a geometric series with the ratio r = -3 and first term a = 4, use the sum of GP formula with n terms and simplify

b) let Sn = -728 and solve for n

c) ehh you could always do guess and check, but if not, then it's solving the biggest value of n in the inequality

since you can make r = 3 (absolute values implies that all values are positive)

d) ahhh just do guess and check
 

Blitz_N7

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Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread


I need help in this question. I can see that Tn=n/2^(n-1) but I dont know how to find Sn.
 

Blitz_N7

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Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread

 

AfroNerd

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Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread

can someone please explain how n only = 27 and not ±27 in the equation n^(2/3) = 9
 

AfroNerd

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Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread

answers say n=27 even though i did those steps
 

InteGrand

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Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread

answers say n=27 even though i did those steps
Was it part of a larger question where n had to be positive (e.g. because it was the number of some objects or something)?
 

AfroNerd

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Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread

Was it part of a larger question where n had to be positive (e.g. because it was the number of some objects or something)?
No, the question just asked to solve. Also, calculators like wolfram alpha only got 27 as well
 

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