Question

Please help!

Write a formula for this sequence: 8, -1, -10, -19,...


Write a formula for this sequence: 1/5, 3/5, 1, 1
2/5

Find the 3rd term in this sequence: tn = 2n/5


Find the fifth term in this sequence: tn = 12 - 2n

Answer 1

First question: sequence is a + (n-1)d...where a is the first term, d = difference,
so 8 + (n-1)(-9)
8 -9n + 9
or, 17-9n

Answer 2

Second question: also an arithmetic sequence whose difference is 2/5...so
1/5 + (n-1)(2/5)
1/5 + 2/5 n - 2/5
or, (2/5)n - 1/5

Answer 3

Third question: Third term of 2n/5

first term, let n = 1, you get 2/5
n = 2, you get 4/5
third term, n = 3, you get 6/5

Third term is 6/5

Answer 4

Now, you can answer the last question, almost identical to the third question.

Answer 5

Ooo. I see now. I missed a step in the first two. Thank you so much!

Answer 6

You're welcome.