Difference between revisions of "1961 AHSME Problems/Problem 3"

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==Problem==
 
If the graphs of <math>2y+x+3=0</math> and <math>3y+ax+2=0</math> are to meet at right angles, the value of ''a'' is:
 
If the graphs of <math>2y+x+3=0</math> and <math>3y+ax+2=0</math> are to meet at right angles, the value of ''a'' is:
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==Solution==
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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.

Revision as of 14:01, 11 December 2012

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.