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Help needed on Sequences and Series :(

Hi all,

I'm new to student room and I needed some help on some Sequences and Series but didnt know how to get the help.

Its AQA Core 2.

Ill post the Question on this link below (not spam) so that you can see trhe full question.

https://pbs.twimg.com/media/BZ1uE9UIcAAHjP1.jpg:large

It is question 7, but feel free to do the others too :biggrin:

Thanks

Arjan M

Reply 1

user2020user

Original post by ArjanM

It is question 7, but feel free to do the others too :biggrin:

This isn't a homework service. Post what you've tried so far and we'll guide you in the right direction.

Reply 2

SherlockHolmes

Original post by ArjanM

...

To get you started, write down all the equation you know from the question using the formula for the general term of an arithmetic sequence.

Reply 3

username976741

Hi, try working through each number and write as follows:

If U1 = 5, then U2 will be (U1)+p which equals 5+p (as U1 is 5 as you're told), then continue with your value with U2.

Reply 4

ArjanM

I've tried doing
5=U0 + P
17=U3 + P in simultaneous equations but that gives me the wrong answer.

I'm not sure what else to try. I've used mymaths and sank earning but they don't have any similar questions.

That's as far as I got I'm afraid.

Reply 5

ArjanM

Original post by aasvogel

Hi, try working through each number and write as follows:

If U1 = 5, then U2 will be (U1)+p which equals 5+p (as U1 is 5 as you're told), then continue with your value with U2.

Provlem is, we know what u1 and u4 is. When I have U2 = 5 + p, I can't work out U3

Reply 6

username976741

Original post by ArjanM

Provlem is, we know what u1 and u4 is. When I have U2 = 5 + p, I can't work out U3

You can't work out an exact value for U3 (yet), but you can write an expression for it:

U3 = (U2)+p

What expression do you have for U2? Substitute that in.

Reply 7

Krollo

Original post by ArjanM

Provlem is, we know what u1 and u4 is. When I have U2 = 5 + p, I can't work out U3

Each is successive term is just the last term add p. You have u2, so you can work out u3 and u4 in terms of p ans from there it's just a simple algebraic equation.

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Reply 8

Mr M

Study Forum Helper

Original post by ArjanM

It is question 7, but feel free to do the others too

Great way to reduce the number of people prepared to help you.

Reply 9

ArjanM

Original post by aasvogel

You can't work out an exact value for U3 (yet), but you can write an expression for it:

U3 = (U2)+p

What expression do you have for U2? Substitute that in.

U2 = 5 + P
U3 = (5+P) + P
17 (u4) = u3+ P

Reply 10

ArjanM

17 = 5 + 2P + P
12 = 3P
4 = P
which is the answer.

Thank you all. I'll try not to ask for any more help again.

thanks all :-)

Reply 11

username976741

Original post by ArjanM

17 = 5 + 2P + P
12 = 3P
4 = P
which is the answer.

Thank you all. I'll try not to ask for any more help again.

thanks all :-)

Well done!

Don't be silly - feel free to ask for as much help as you need on this forum, I ask for help when I need it too. What people are saying is that we're to help and not to give you the answers straight away; to come to your own conclusions rather than us simply feeding you the answer. :smile:

Reply 12

ArjanM

Original post by aasvogel

Thank you :-) I wasn't happy with my Core 2 grade and I'm retaking it in June so I was just going over the topics again.

Thanks again for the help.

ArjanM

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Reply 13

username976741

Original post by ArjanM

Thank you :-) I wasn't happy with my Core 2 grade and I'm retaking it in June so I was just going over the topics again.

Thanks again for the help.

ArjanM

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Good luck, and you're welcome!

Reply 14

Super199

Original post by ArjanM

Thank you :-) I wasn't happy with my Core 2 grade and I'm retaking it in June so I was just going over the topics again.

Thanks again for the help.

ArjanM

Posted from TSR Mobile

If you don't mind me asking what grade did you get last time? And what topics do you think are the hardest in Core 2?