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Another GMAT prep PS questn

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by jimmiejaz » Mon Nov 17, 2008 4:34 am
supershick wrote:Rey, thanks for the response,

I understand what you're saying but the question does ask "...what two points intersect the x-axis..."

The two points are (0,-a) and (0,-b), right?
Now that we have that, if we have enough data to pinpoint the values of 'a' and 'b', then we're good to go right?

With the two pieces of information combined, the possible values for 'a' are -3 and 2. The two possible values for b are -3 and 2 as well.

I gathered this information from (2), "ab = -6" and from (1), "a + b = -1". Solving for 'a' and 'b' would give the aforementioned values right? To fulfill the data given, it can be (-3)(2) = -6 or (2)(-3) = -6. Therefore, the values for 'a' and 'b' change.

This is my thinking process. I must be thinking way too deeply into this. Haha.
Hey supershick,

First of all the points will be (-a,0) and (-b,0)
since at x=-a or x=-b, y=0.
Anyways, your approach is also correct. But you are getting confused at the last step.
Lets go with your approach. Indeed a can be -2 or 3 and b can be -2,3.
Lets try both. It will give you your mistake.
when a = 2, coordinates are (-2,0)
when a = -3, coordinates are (3,0)
when b = 2, coordinates are (-2,0)
when b = -3, coordinates are (3,0)

So, even with both the values it returns us the same set of coordinates.
Hence the values of a and b doesnt matter.
Hope it clarifies......

Rajiv
What if i have not yet beat the beast, I know i will beat it!!!!!!!!
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by independent » Mon May 28, 2012 5:40 am
supershick wrote:Rey, thanks for the response,

I understand what you're saying but the question does ask "...what two points intersect the x-axis..."

The two points are (0,-a) and (0,-b), right?

Now that we have that, if we have enough data to pinpoint the values of 'a' and 'b', then we're good to go right?

With the two pieces of information combined, the possible values for 'a' are -3 and 2. The two possible values for b are -3 and 2 as well.

I gathered this information from (2), "ab = -6" and from (1), "a + b = -1". Solving for 'a' and 'b' would give the aforementioned values right? To fulfill the data given, it can be (-3)(2) = -6 or (2)(-3) = -6. Therefore, the values for 'a' and 'b' change.

This is my thinking process. I must be thinking way too deeply into this. Haha.

I don't understand how did you get that ab=-6, and why are the two points (0,-a) and (0,-b).

EDIT: Nevermind I got it :)
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