OE
With a little number picking for x,y,
and k
or with a basic understanding of curved lines in the coordinate geometry plane, you can see that this parabola opens upward, is centered on the y axis, and has its lowest point (vertex) above the x axis (because k
is positive). The most important part of this problem is making sure that you have a proper visual representation of this parabola, so make sure that you take time to make a quick sketch before you start to analyze each statement.
If line L intersects this parabola at exactly one point, then visually you can see different possibilities along the parabola if you've drawn it correctly. The only possible intersection points are clearly in Quadrants I and II as the parabola does not even enter the other two quadrants. The question is asking whether that intersection point is in quadrant I or not.
Statement 1 tells you that line L has a positive slope. If you draw a few lines with positive slopes that only intersect the parabola at one point, you you can see that no matter the line, it must intersect the parabola in the 1st quadrant. If the slope is 0 (which is not allowed), then it would intersect at the y axis, and as the slope moves from 0 to infinity it can only intersect in the 1st quadrant. Statement 1 is sufficient. Eliminate (B), (C), and (E).
Statement 2 tells you that x
is positive which necessarily limits the intersection points to the 1st quadrant as all x
values in the 2nd quadrant are negative. Statement 2 is also sufficient and the answer is (D).