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随着日常生活和生产的需要,正数和负数在许多方面被广泛地应用.下面举例加以说明.一、用正数和负数表示两种相反的移动方向例1一只小船在湖里漂流,小船先向正南方向漂流300m,再向正北方向漂流250 m,接着又向正南方向漂流400 m,最后向正北方向漂流150 m.如果向正南方向漂流用正数表示,则上述漂流过程用正数和负数可表示为____.分析:正南和正北是两种相反的方向,方向改变,数的性质符号也应改变;反之,若数的性质符号改变,则对应的方向也应改变.
With the needs of daily life and production, positive and negative are widely used in many aspects, as an example to illustrate one, with positive and negative numbers indicate two opposite directions of movement Example 1 a boat drifting in the lake, The boat first drifted 300 m to the south and drifted 250 m to the north and then rammed 400 m to the south and drifted 150 m to the north and if drifting toward the south were positive, Drifting process with positive and negative can be expressed as ____. Analysis: positive and positive North are two opposite directions, the direction of change, the nature of the number of symbols should be changed; the other hand, if the nature of the symbol changes, the corresponding direction It should also change.