SOLUTION: Which of the following functions represents a direct variation? Answer y = x2 y = -8x y =-2/x y = x3

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Question 687866:
Which of the following functions represents a direct variation?
Answer

y = x2

y = -8x

y =-2/x

y = x3

Found 2 solutions by stanbon, MathLover1:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Which of the following functions represents a direct variation?
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Definition of Direct Variation:
In mathematics, two quantities are said to be proportional if they vary in such a way that one of the quantities is a constant multiple...
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Answer
y = x^2----No
y = -8x----Yes
y = -2/x----No
y = x^3-----No
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Cheers,
Stan H.
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Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

The statement " y varies directly as x ," means that when x increases, y increases by the same factor. In other words, y and x always have the same ratio:
y%2Fx=+k+ where k is the constant of variation.
We can also express the relationship between x and y as:
y+=+kx+

so, your answer is: y+=+-8x where k=-8