gabriel wrote:4)In the xy-plane, line L passes through point (1,p). Does L have a positive slope?
1). L passes through point (-p, 13)
2). L passes through point (0,1)
One more E
1 - Insufficient. slope = p-13 / 1+p. Need value of p to evaluate slope
2 - Insufficient. slope = p-1. Again need p.
1 & 2 together insufficient.
slope of line connecting (-p,13) and (0,1) = -12/p. This should be
equal to slope in either 1 or 2.
-12/p = p-1 implies p^2 - p + 12 = 0. No solution exists. This proves
that there cannot be a line that passes through these points and
hence E.
