Explanation:
- 9 feet
- 10 feet (10 ft = 10·12 in = 120 in)
- 130 inches
- 12 feet (12 ft = 12·12 in = 144 in)
- 145 inches
_____
Obviously, 9 < 10 < 12, so ordering by feet is easy. Then we need to figure out where the inch measurements belong.
1 foot = 12 inches, so we can figure some references to use to compare to the inch measurements.
10 feet = 10·12 in = 120 in, so 130 in is longer, by less than 1 ft.
12 feet = 12·12 in = 144 in, so 145 in is longer.
224 hours and 43 seconds.
Answer:
See below.
Step-by-step explanation:
Convert the cotangent to cosine over sine:
Use the cofunction identities. The cofunction identities are:
To convert this, factor out a negative one from the cosine and sine.
Recall that since cosine is an even function, we can remove the negative. Since sine is an odd function, we can move the negative outside:
Answer:
a) -7/9
b) 16 / (n² + 15n + 56)
c) 1
Step-by-step explanation:
When n = 1, there is only one term in the series, so a₁ = s₁.
a₁ = (1 − 8) / (1 + 8)
a₁ = -7/9
The sum of the first n terms is equal to the sum of the first n−1 terms plus the nth term.
sₙ = sₙ₋₁ + aₙ
(n − 8) / (n + 8) = (n − 1 − 8) / (n − 1 + 8) + aₙ
(n − 8) / (n + 8) = (n − 9) / (n + 7) + aₙ
aₙ = (n − 8) / (n + 8) − (n − 9) / (n + 7)
If you wish, you can simplify by finding the common denominator.
aₙ = [(n − 8) (n + 7) − (n − 9) (n + 8)] / [(n + 8) (n + 7)]
aₙ = [n² − n − 56 − (n² − n − 72)] / (n² + 15n + 56)
aₙ = 16 / (n² + 15n + 56)
The infinite sum is:
∑₁°° aₙ = lim(n→∞) sₙ
∑₁°° aₙ = lim(n→∞) (n − 8) / (n + 8)
∑₁°° aₙ = 1
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