1951 AMC 12 Problem 17

Attempt Problem 17 of the 1951 AMC 12 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1951 AMC 12 solutions, or check the answer key.

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17.

Indicate in which one of the following equations

y

is neither directly nor inversely proportional to

x

x+y=0

3xy=10

x=5y

3x+y=10

\dfrac{x}{y}=\sqrt3

Direct proportion has the form

y=kx

, while inverse proportion has the form

xy=k

Rewrite each equation by solving for

y

Choices A, C, and E rearrange to

y=kx,

and choice B rearranges to

xy=k.

But choice D gives

y=10-3x,

which is neither form.

Thus, the correct answer is D.

Problem 17 in other years