Question 574725
Strategy is to find the slope of both equations.  If the slopes are "negative reciprocal" the two lines are perpendicular.  That is, the slopes multiplied results in -1.
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A)2x - 8y = 9 & 12x - 3y = 7
slope of:
2x - 8y = 9
-8y = -2x+9
8y = 2x-9
y = (1/4)x-9/8 (slope is 1/4)
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slope of:
12x - 3y = 7
-3y = -12x+7
3y = 12x-7
y = 4x-7/3 (slope is 4)
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4(1/4) = 1 (NO, not perpendicular)
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B)3x + 6y = 8 & y = 2x - 8
slope of:
3x + 6y = 8
6y = -3x+8
y = (-1/2)x+8/6 (slope is -1/2)
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slope of:
y = 2x - 8  (slope is 2)
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(-1/2)(2) = -1  (YES, it is perpendicular)

No need to solve the last two..
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C)y = 2x - 7 & x + y = 3
D)2y = -3x +5 & 2x + 3y = 4