Is the line through points P(4,9) and Q(1,8) parallel to the line through points R(-1,2) and S(-5,0)? Explain
A) no; one line has zero slope, the other has no slope
B) yes; the lines have equal slops
C) yes; the lines are both vertical
D) no; the lines have unequal slopes

Question

Is the line through points  P(4,9) and Q(1,8) parallel to the line through points R(-1,2) and S(-5,0)? Explain 
A) no; one line has zero slope, the other has no slope 
B) yes; the lines have equal slops 
C) yes; the lines are both vertical 
D) no; the lines have unequal slopes

anonymous · Answer

Slope of PQ = (8-9)/(1-4) = 1/3
Slope of RS = (0-2)/(-5 - -1) = -2/-4 = 1/2

Since the slopes are UNEQUAL, the lines are NOT parallel.

Choice (D).