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| Question 517702:  find the equation of line which is perpendicular to line y=5x+9 and has y-intercept=6
 Answer by gc2000(22)
      (Show Source): 
You can put this solution on YOUR website! summary: slope = m and y-intercept = b when line is expressed as y=mx+b
 Parallel lines have the same slope, perpendicular lines have slopes that are "negative reciprocals" (for example, if slope of a line is 3, then -1/3 is the slope for all perpendicular lines; if slope is 1/2, perpendicular slopes are -2, etc.).
 
 y=5x+9
 since slope is 5, all perpendicular lines have slope = -1/5
 since y-intercept is 6, "b"=6 in formula: y=mx+b
 
 substitute in -1/5 and 6 into y=mx+b:
 y=(-1/5)x+6
 
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