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Coordinate Geomertry
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[email protected]
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Mani_mba
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y = (x+a)(x+b)
y = x^2 + x(a+b) + ab ---> ST1
If we look at statement 1, a+b = -1
So the eqn becomes y = x^2 - x + ab
This is insufficient as a and b are unknown...
Look at statement 2, the curve intersects y -axis at (0,-6)
Substituting these values in ST1, we imply ab=-6. But still this is insufficient as a+b is unknown.
Combining statement 1 and 2, we get y = x^2 -x -6
In x axis , y = 0. So x^2 -x -6 = 0
x = 3,-2.. The points are (3,0) and (-2,0)
Hence C.
y = x^2 + x(a+b) + ab ---> ST1
If we look at statement 1, a+b = -1
So the eqn becomes y = x^2 - x + ab
This is insufficient as a and b are unknown...
Look at statement 2, the curve intersects y -axis at (0,-6)
Substituting these values in ST1, we imply ab=-6. But still this is insufficient as a+b is unknown.
Combining statement 1 and 2, we get y = x^2 -x -6
In x axis , y = 0. So x^2 -x -6 = 0
x = 3,-2.. The points are (3,0) and (-2,0)
Hence C.
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cubicle_bound_misfit
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Hi,
I had no idea that Vue gives second degree equation for Co ordinate in GMAT exam.
Ian, if possible Please put some light on that.
But for this problem,
X-axis intersect will happen when y=0 i.e. (x+a)(x+b)=0
so we need to find value for both a and b which is possible when we combine both the stmt.
Ans C.
regards,
I had no idea that Vue gives second degree equation for Co ordinate in GMAT exam.
Ian, if possible Please put some light on that.
But for this problem,
X-axis intersect will happen when y=0 i.e. (x+a)(x+b)=0
so we need to find value for both a and b which is possible when we combine both the stmt.
Ans C.
regards,
Cubicle Bound Misfit
GMAT/MBA Expert
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Ian Stewart
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Yes, you can certainly see second degree equations- and a lot of other kinds of equations- in GMAT co-ordinate geometry, but you don't need to know much about them. The question above is typical; you need to know how to find x-intercepts (set y = 0), but you don't even need to know that the equation represents a parabola. As long as you know the basics in co-ordinate geometry - equations for lines, what the slope means, how to find x and y intercepts, how to calculate distances, how to graph things, etc - you should be fine; no need to learn the equations for ellipses or hyperbolas or anything like that.cubicle_bound_misfit wrote:Hi,
I had no idea that Vue gives second degree equation for Co ordinate in GMAT exam.
Ian, if possible Please put some light on that.
\
regards,
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com
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