Monday, May 4, 2009

Problem 26 - GMAT Coordinate Geometry

In a coordinate system, line l is parallel to line k, does line l intersect the x-axis?

(1) Line k has slope zero.

(2) Point (0, 4) is on line k.


  1. (1) y = constant has 0 slope, which is parallel to x axis. l is parallel to x axis. (A) and (D)

    (2) line k intersects with y axis. So, line l intersects with y axis. Nothing abt x-axis.

    Answer is A

  2. Answer should be, E.

    Proving that line is parallel to x-axis isn't enough to prove that doesn't intersect x-axis. We need to prove that the line is not co-incident as well.

    If two lines are co-incident lines, they intersect each other at all points.

    Both (1) & (2) tell us that k is not co-incident with x-axis.

    But they don't tell us whether line l is co-incident with x-axis.

    Hence, we can't say if l intersects x - axis.

  3. This comment has been removed by the author.

  4. Eternity is right
    1: k is parallel to X Aaxis
    l maybe co-incident with the X axis.
    2: Again it doesnt tell us whether l passes through x axis or not.
    1 & 2: K is parallel to the x axis and offset by 4 units. It doesnt tell us anything about l
    Answer E

  5. Eternity is v right..:)
    v good explanation

  6. This is a tricky question.The game is hidden in words. Still not sure, which option is correct.