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OG12 # 94

by KItuz » Sun Jun 12, 2011 6:54 pm
Not sure why the answer is A instead of D. Can you not determine the value of m and b given the point of intersection and the line it intersects? Can someone explain why the answer is A?
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Source: — Data Sufficiency |

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by Anurag@Gurome » Sun Jun 12, 2011 8:13 pm
KItuz wrote:Not sure why the answer is A instead of D. Can you not determine the value of m and b given the point of intersection and the line it intersects? Can someone explain why the answer is A?
It is always better to post the question also.

The equation of line k is y = mx + b, where slope of line k is m.

From statement 2, y = mx + b intersects y = 2x + 3 at the point (2, 7).
So, (2, 7) will satisfy both the equations.
So, when we put x = 2 and y = 7 in y = mx + b, we get 7 = 2m + b. But we have just one equation and 2 variables. So, (2) is NOT SUFFICIENT.
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by KItuz » Mon Jun 13, 2011 5:35 am
Point of intersection of line mx - y + b = 0 and 2x - y + 3 = 0 = (2,7) gives us 2 equations 2m-b-1=0 and 2m+b-7=0 can we not find out m and b from these 2 equations?
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