Help maths

Help I don’t know why the maximum n value is 16 for part b.
How did they go from the 3rd last line to the second last line???

(edited 11 months ago)

Reply 1

Lah bushâ€™s Bla

9

In order to find the biggest S value, you have to find the last term in the series that is positive. So the equation is, 9300-600(n-1) > 0. You'll get n < 16.5, so the maximum n value is 16 as it has to be whole number.

Edit: Oh if you are following the marking scheme. Sn = 96000n - 300n^2. You want to find maximum Sn value, all you have to do is to differentiate the equation, and find the n value when derivative of Sn equals to zero

(edited 11 months ago)

Reply 2

Alevelhelp.1

OP

15

Original post by Lah bush’s Bla

In order to find the biggest S value, you have to find the last term in the series that is positive. So the equation is, 9300-600(n-1) > 0. You'll get n < 16.5, so the maximum n value is 16 as it has to be whole number.

Edit: Oh if you are following the marking scheme. Sn = 96000n - 300n^2. You want to find maximum Sn value, all you have to do is to differentiate the equation, and find the n value when derivative of Sn equals to zero

Thanks…
Also for this question I don’t get how do do this (I put the marking scheme in Black pen on the paper plz guide me I don’t get it 😭 I’m gonna fail

Part B

(edited 11 months ago)

Reply 3

Lah bushâ€™s Bla

9

Original post by Alevelhelp.1

Thanks…
Also for this question I don’t get how do do this (I put the marking scheme in Black pen on the
paper plz guide me I don’t get it 😭 I’m gonna fail

Part B

Ummm it’s quite straightforward. To find the range of a, you can first find the range of r, which is -1 < r < 1. Then you add 1 to both side of inequality and multiply by 2, because a=2(r+1). Now you have 2(1+(-1)) < 2(1+r) < 2(1+(1)), therefore 0 < a < 4

Help maths

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you