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
The correct answer would be C
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Answer:
The ladder reach a height 8.485 ft.
Step-by-step explanation:
The ladder with the building made right angle triangle
The length of the ladder is the hypotenuse 12 ft.
The angle between the ladder and the building is 45°
The height of the ladder reach is the vertical side of the Δ
∴ h = 12 cos 45° = 6√2 = 8.485 ft.
-7 is losing the fewest as it is the smallest number, and the number that is to the left of the number line.