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Algebra Difficulty 3.1 AMC 10/12 Find the answer

The graph of y=logxy=\log x
(A) Cuts the y-axis\textbf{(A)}\ \text{Cuts the }y\text{-axis}(B) Cuts all lines perpendicular to the x-axis\\ \textbf{(B)}\ \text{Cuts all lines perpendicular to the }x\text{-axis}(C) Cuts the x-axis\\ \textbf{(C)}\ \text{Cuts the }x\text{-axis}(D) Cuts neither axis\\ \textbf{(D)}\ \text{Cuts neither axis}(E) Cuts all circles whose center is at the origin\\ \textbf{(E)}\ \text{Cuts all circles whose center is at the origin}

This was a multiple-choice question, but the options didn't survive into the source we have. The answer given is \textbf{(C)}\, and the solution below works it through.

Solution

The domain of logx\log x is the set of all positive\underline{positive} reals, so the graph of y=logxy=\log x clearly doesn't cut the yy-axis. It therefore doesn't cut every line perpendicular to the xx-axis. It does however cut the xx-axis at (1,0)(1,0). In addition, if one examines the graph of y=logxy=\log x, one can clearly see that there are many circles centered at the origin that do not intersect the graph of y=logxy=\log x. Therefore the answer is (C) Cuts the x-axis\boxed{\textbf{(C)}\ \text{Cuts the }x\text{-axis}}.

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Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.