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# C2 Question Watch

1. a sequence of numbers u1,u2,…,un,…is given by the formula un=3(2/3)^n-1

show that S15 =-9.014

I did the first part of the question i can't prove the second part. Can I not show that it works by plugging two different U values in?

Prove that Un+1=2(2/3)^n-1
2. Can I just ask if this for as or a2 and is it hard because looking at some of these questions is maybe me doubt whether I'd cope at this subject!
3. (Original post by thelion0)
a sequence of numbers u1,u2,…,un,…is given by the formula un=3(2/3)^n-1

Prove that Un+1=2(2/3)^n-1
Is this the bit you're stuck on?

Just put n+1 into the formula for and it all drops out once you simplify a bit
4. (Original post by davros)
Is this the bit you're stuck on?

Just put n+1 into the formula for and it all drops out once you simplify a bit
i tried everything I need someone to show me
5. (Original post by Victoriapownall)
Can I just ask if this for as or a2 and is it hard because looking at some of these questions is maybe me doubt whether I'd cope at this subject!
AS
6. (Original post by thelion0)
i tried everything I need someone to show me
Well what do you get if you replace n with n+1 in the very first formula?
7. Someone else help OP is worthless
8. (Original post by thelion0)
Someone else help OP is worthless
You haven't answered my question from the previous post! What do you get if you put n+1 in place of n in the formula you've been given?
9. (Original post by thelion0)
AS
Ahhhhhhhhhh......I'm scared of failing now!
10. (Original post by Victoriapownall)
Ahhhhhhhhhh......I'm scared of failing now!
It only looks scary because you're not familiar with all the symbols and things! Once you start learning it you'll be fine

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