Co-ordinate geometry - How to solve
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Source: Beat The GMAT — Data Sufficiency |
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jayhawk2001
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eqn of line l : y = m1*x + c1
eqn of line k : y = m2*x + c2
1 - insufficient. product of x intercepts = (-c1/m1) * (-c2/m2)
= c1c2 / m1m2 = +ve. We don't know if m1m2 is +ve or -ve
2 - insufficient. We just know c1c2 = -ve
Combining 1 and 2, we know m1m2 is negative. So, sufficient. Hence C.
The loose end here is the data-point (4,3) that I have not used
anywhere...
eqn of line k : y = m2*x + c2
1 - insufficient. product of x intercepts = (-c1/m1) * (-c2/m2)
= c1c2 / m1m2 = +ve. We don't know if m1m2 is +ve or -ve
2 - insufficient. We just know c1c2 = -ve
Combining 1 and 2, we know m1m2 is negative. So, sufficient. Hence C.
The loose end here is the data-point (4,3) that I have not used
anywhere...
