piyush_nitt wrote:DanaJ wrote:If the line with the equation y = 3x + 2 contains the point (r,s), then this equivalent to s = 3r + 2. If we ca prove that, then we're home free.
1. this equation equals 0 only if one or both of the two paranteses are equal to 0. So we get:
If 3r + 2 - s = 0, which is equivalent to s = 3r + 2, then indeed the poin is on the said line.
But this could not be the case. If 4r + 9 - s = 0 but 3r + 2 - s does not equal 0, then the point is noton the line. So 1 is not sufficient.
2. using the same line of thought as before, 2 is insufficient as well.
But if we take the two equations togethere, then it is clear that only if 3r + 2 - s = 0 do they both equal 0, because if we were to consider 4r + 9 - s = 4r - 6 -s = 0, then we get that 9 = -6, which is obviously false. So answer would be C.
Great Thanks !!
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IMO C, with two points to ponder:
1. What made us believe here that 3r + 2 - s does not equal 0? We can take 4r + 9 - s = 4r - 6 - s = 0, only when we are convinced that 3r + 2 - s does not equal 0, because division by zero is not defined. And once we acknowledge 3r + 2 - s does not equal 0, question is answered. How? And what would have been the answer in that situation, links?
2. Moreover, even if the figures would have been meaningful (I mean if we were to take 4r + A - B s = 4r - C - D s = 0, where A, B, C, and D were different real numbers so chosen that it should not lead to a meaningless situation), the answer to this question would still have been C. Why?
