Find the 10th partial sum of the arithmetic sequence defined by (An)={1/2n-1/2}

Answer 1

a(1) = (1/2)(1) - 1/2 = 0
a(2) = (1/2)(2) - 1/2 = 1/2
a(3) = (1/2)(3) - 1/2 = 1
....
looks like an arithmetic sequence with a = 0, d = 1/2

sum(n) = (n/2)(2a + (n-1)d )

your turn .....

Answer 2

So 4.5?

Answer 3

no, how did you get 4.5 ???

sum(10) = 5(0 + 9(1/2))
= 5(4.5)
= 22.5

Answer 4

1. D 42.5
2. A s9=9/2(2+26)
3. B 22.5
4. D 617.5
5. A 425.25

Answer 5

If An is arthimetic sequence with A1=5, A5=21 find partial sum s30, An is equal to...

Answer 6

Step 1: Find the common difference:
d = (A5 - A1)/(5 - 1) = 4

Step 2: Find the nth term formula:
An = A1 + (n-1)d

Step 3: Use the nth term formula to find A30:
A30 = 5 + (30-1)(4) = 117

Step 4: Use the sum formula to find the partial sum S30:
S30 = (30/2)(A1 + A30)
S30 = (15)(5 + 117)
S30 = 1815

Therefore, the partial sum S30 of the arithmetic sequence with A1 = 5 and A5 = 21 is 1815. The nth term formula is An = 5 + (n-1)4.