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by resilient » Sun Feb 17, 2008 11:27 pm
Which of the following equations represents a line that is perpendicular to the line described by the equation 3x + 4y = 8 ?
a.3x + 4y = 18
b.3x – 4y = 24
c.4y – 3x = 26
d.1.5y + 2x = 18
e.8x – 6y = 24

qa is e i chose d
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by gmatjoe » Mon Feb 18, 2008 8:11 am
I solved this question through elimination of the answers, because it's not mentioned at which coordinate the 2 lines crosses each other:

Rewrite 3x+4y=8 to y=-3/4(x)+2

Perpendicular line to this function must have positive slopes: eliminate answers (a) and (d).

Furthermore, slope must be inverse, thus answer must read y=4/3(x)+something: eliminate answer (b) and (c), leaving (d) as the correct answer.

Hope this helps. Joe.