The given sequence is
a₁, a₂, ...,

Because the given sequence is an arithmetic progression (AP), the equation satisfied is

where
d = the common difference.
The common difference may be determined as
d = a₂ - a₁
The common difference is the difference between successive terms, therefore
d = a₃ - a₂ = a₄ - a₃, and so on..
The sum of the first n terms is

Example:
For the arithmetic sequence
1,3,5, ...,
the common difference is d= 3 - 1 = 2.
The n-th term is

For example, the 10-term is
a₁₀ = 1 + (10-1)*2 = 19
Th sum of th first 10 terms is
S₁₀ = (10/2)*(1 + 19) = 100
Answer:
1: 18.75
Step-by-step explanation:
We multiply both sides by 5.
Answer:
a. 12 yd
Step-by-step explanation:

Answer:
A) 10,560 ft. B) 32 more laps.
Step-by-step explanation:
A) Four laps around a track is equal to one mile, and there are 5,280 feet in one mile. If Roger ran eight laps, he ran two miles. Therefore: 5,280 ft. times 2, is equal to 10,560 ft.
B) We know that Roger ran two miles Monday. We also know that four laps around a track is equal to one mile. In order to run 10 miles, he would have to run 40 laps, and since he already ran 8, we can subtract that from 40. You are left with 32 more laps.
<h3>
Answer: Choice C) 421.9</h3>
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Explanation:
You're on the right track. You wrote down the proper expression to get the final answer, assuming you meant to write 75/4 as the third term inside the parenthesis. This works because each time you cut the side length in half to get each smaller triangle's side. The 3 is because there are 3 sides for each of the triangles. Much of this I have a feeling you already know as you wrote down the expression on the page, though I'm not 100% sure of your mindset. Computing this expression leads to 421.875 which rounds to 421.9
note: an alternative is to write 3*75 + 3*75/2 + 3*75/4 + 3*75/8, though that is more work. It's better to have that 3 factored out.