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1961 AHSME Problems/Problem 3

Revision as of 14:01, 11 December 2012 by Brian22 (talk | contribs)

Problem

If the graphs of $2y+x+3=0$ and $3y+ax+2=0$ are to meet at right angles, the value of a is:

Solution

The slope of the first graph is -1/2. The slope of the second is 2, since it is perpendicular, and it is also -a/3 by rearranging. Thus a=-6.

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