Answer: <u><em>512</em></u>
Step-by-step explanation: <u><em>the length of a varies string varies inversely as the frequency of its vibrations. A violin string 10 inches long vibrates at a frequency of 512 cycles per second. Find the frequency of an 8-inch string.</em></u>
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Answer:
512
Step-by-step explanation:
Suppose we ask how many subsets of {1,2,3,4,5} add up to a number ≥8. The crucial idea is that we partition the set into two parts; these two parts are called complements of each other. Obviously, the sum of the two parts must add up to 15. Exactly one of those parts is therefore ≥8. There must be at least one such part, because of the pigeonhole principle (specifically, two 7's are sufficient only to add up to 14). And if one part has sum ≥8, the other part—its complement—must have sum ≤15−8=7
.
For instance, if I divide the set into parts {1,2,4}
and {3,5}, the first part adds up to 7, and its complement adds up to 8
.
Once one makes that observation, the rest of the proof is straightforward. There are 25=32
different subsets of this set (including itself and the empty set). For each one, either its sum, or its complement's sum (but not both), must be ≥8. Since exactly half of the subsets have sum ≥8, the number of such subsets is 32/2, or 16.
Answer:
∠ 4 = 130°
Step-by-step explanation:
The exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.
∠ 4 is an exterior angle of the triangle , so
∠ 4 = ∠ 1 + ∠ 2 ( substitute values )
11x + 9 = 6x + 6 + 4x + 14 , that is
11x + 9 = 10x + 20 ( subtract 10x from both sides )
x + 9 = 20 ( subtract 9 from both sides )
x = 11
Then
∠ 4 = 11x + 9 = 11(11) + 9 = 121 + 9 = 130°
your friend may have only calculated ∠ 1
∠ 1 = 6x + 6 = 6(11) + 6 = 66 + 6 = 72°
Answer:
49º
Step-by-step explanation:
Y=3(-3) x 2
y= -9 x 2
y=-18
.............
