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《中小学数学(初中版)》2012年1-2期刊登杨军的《不同的解法不同的结论》一文.后又看到了几篇研究此问题的文章,多采用高中知识来解决.其实完全可用初中知识来解决.原题如下:如图,在平面直角坐标系xoy中,已知抛物线y=-1/3x~2+1/3x+4与y轴相交于点B,与x轴相交于A、C两点.(1)求A、B、C三点的坐标;(2)已知有一动点P从点A沿线段AC以每秒1个单位长度的速度移动;同时另一动点Q以同一速度从点B沿线段BC移动,当其中一个动点到达端点时,另一个动点也随之停止;设运动时间为t秒.
“Primary and Secondary Mathematics” (Junior High School Edition) “2012 the 1-2 issue of Yang Jun’s” different solutions to different conclusions "article .And later saw several articles to study this issue, more use of high school knowledge to solve .In fact, complete Available in junior high school knowledge to solve. The original title is as follows: As shown in the plane Cartesian coordinate system xoy, the known parabola y = -1 / 3x ~ 2 + 1 / 3x + 4 and y axis intersect at point B, (1) Seeking the coordinates of three points of A, B and C; (2) It is known that a moving point P moves along the line segment AC from point A at the rate of 1 unit length per second; at the same time, another moving Point Q moves from point B along line BC at the same speed. When one of the points reaches the end point, the other point stops. The movement time is t seconds.