In the xy-plane, line l and line k intersect at the point (16/5, 12/5). What is the slope of line l?
(1) The product of the slopes of line l and line k is –1.
(2) Line k passes through the origin.
(1) Tells us that the two lines are perpendicular. But it does not help us to find the slope of line l. So not suff.
(2) tells us that apart from (16/5,12/5), line k passes through origin (0,0). But no info about line l. So not suff.
When combined. (2) helps us find the slope of k. and (1) helps us find the slope of l using the slope of k (slope l *slope k =-1).
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