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# Artihmetic Sequences! watch

1. Just stuck on how to do this question!
The sequences of terms U1, U2, U3... is defined by
U1=8 Un+1=AUn +1 where a is a negative constant
The third term of the sequence is U3=2.68
Find the value of a

Thankyou!

---Moved to Maths---
2. (Original post by Megan.Rose..)
Just stuck on how to do this question!
The sequences of terms U1, U2, U3... is defined by
U1=8 Un+1=AUn +1 where a is a negative constant
The third term of the sequence is U3=2.68
Find the value of a

Thankyou!
Sticking to algebra, run through the formula until you get to n=3 writing out everything you see (brackets are your friend), You should be able to solve from there
3. (Original post by Megan.Rose..)
Just stuck on how to do this question!
The sequences of terms U1, U2, U3... is defined by
U1=8 Un+1=AUn +1 where a is a negative constant
The third term of the sequence is U3=2.68
Find the value of a

Thankyou!
Can you find U_3 in terms of A?
4. (Original post by Megan.Rose..)
Just stuck on how to do this question!
The sequences of terms U1, U2, U3... is defined by
U1=8 Un+1=AUn +1 where a is a negative constant
The third term of the sequence is U3=2.68
Find the value of a

Thankyou!

---Moved to Maths---
You should be able to get U_3 as a quadratic in A, and this will have one negative root which will be the value of A.

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