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【OG20-P287-386题】
On the number line, point R has coordinate r and point T has coordinate t. Is t < 0 ?
(1) -1 < r< 0
(2) The distance between R and T is equal to r2
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条件1:不充分
条件2:不充分
1+2:|r^2|<|r|→t<0,充分
题目讨论 (10条评论)

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你这只猪
画图直接列举数字,-1
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0 回复 2020-06-08 14:04:01
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cindyGMAT330
这样讲, 当-1
t=-(r^2 + r ) 那t就是负数; 另外 coordinate是坐标的意思 数字线上的坐标 应该就是指数字吧。 开始我看到coordinate也纠结了好久 xy数轴的话 根本没法思考了。。。 0
1 回复 2019-11-21 16:47:21
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cindyGMAT330
这样讲, 当-1
-t=r^2 + r => t=-(r^2 + r ) 那t就是负数; 另外 coordinate是坐标的意思 数字线上的坐标 应该就是指数字吧。 开始我看到coordinate也纠结了好久 xy数轴的话 根本没法思考了。。。 0
0 回复 2019-11-21 16:46:10
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cindyGMAT330回复cindyGMAT330
为什么我打字不能完整。。。 奇怪
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0 回复 2019-11-21 16:47:50
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波波lll
这道题在说什么……没有一个单词不认识却看不懂
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0 回复 2019-11-05 16:23:21
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想养一只博美
条件1:-1
0,有r-t=r^2,即t=r(1-r),已知条件1有 -1 0,有t-r=r^2,即t=r(1+r),条件1有-1 0
0 回复 2019-10-24 13:37:37
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shadow99
是有图的吗。。。
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0 回复 2019-07-20 16:12:19
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Jess123
1+2:f-r=r2,f=r2+r>0充分
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0 回复 2019-03-31 16:47:51
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ziyuanguo
什么意思啊
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0 回复 2019-01-28 18:02:22
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驴子旋呀
bb h Statement Two Alone: The distance between R and T is equal to r^2. The distance between two values on the number line is the absolute value of the difference between the two values. Thus statement two gives us the equation |r - t| = r^2. However, without knowing anything about r and t, we can’t determine whether t is less than zero. For instance, r could be 2 and t could be -2; or r could be -2 and t could be 2. In each of the cases, |r - t| = 4 = r^2; but in one case t > 0 and in the other t < 0. Statement two is not sufficient to answer the question. We can eliminate answer choice B. Statements One and Two Together: Using statements one and two, we know that r is a negative proper fraction and |r - t| = r^2. Thus, r - t = r^2 OR r - t = -r^2. Solving each of these for t, we get: t = r - r^2 OR t = r + r^2. Since r is a negative proper fraction, no matter what the value of r is, t will always be a negative number. For instance, if r = -1/2, then r^2 = 1/4 and t will either be -1/2 - 1/4 = -3/4 or -1/2 + 1/4 = -1/4. The reason why t cannot be positive is that when we square r (a negative proper fraction), the value of r^2 (though positive) will be less than the absolute value of r. Recall that t = r - r^2 or t = r + r^2. When a positive proper fraction with a smaller absolute value is added to (or subtracted from) a negative proper fraction with a larger absolute value, the sum (or difference) will always be less than zero. Answer: C https://gmatclub.com/forum/on-the-number-line-point-r-has-coordinate-r-and-point-t-has-coordinat-220426.html
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0 回复 2018-10-19 14:22:00
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phylliskong38
在左边,r-t=r^2, t<0 在右边,t-r=r^2, t<0 所以联立t<0,充足
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0 回复 2018-08-28 22:54:09