Question 77934
Lines that are perpendicular have slopes that are the negative reciprocal of each other:
Example: if Line #1 and Line #2 are perpendicular, than Slope #1 = 2 and SLope #2=-1/2.

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If line #1=y=4x-7, than the slope of line #2 = -1/4
Points (0, 0) represents the y-intercept of line #2 (0, b).  Therefore, the slope of Line #2 = -1/4 and the y-intercept = (0) or:
y=-1/4x+0 
y=-1/4x

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Graphing:
{{{ graph( 300, 200, -6, 5, -10, 10, 4x-7, (-1/4)x) }}}