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在教学过程中,我发现北师大版数学教材对分式(数)的处理有点繁琐,呈现出来,供大家探讨.例1计算:(1)cos60°+sin45°-tan30°(2)6tan~230°-3~(1/2)sin60°-2cos45°教师用书上提供的参考答案是:(1)(3+32~(1/2)-23~(1/2))/6(2)(1-22~(1/2))/2这两个答案太过繁琐,我认为这样写更为简洁:(1)1/2+1/22~(1/2)-1/33~(1/2)(2)1/2-2~(1/2)其实不是同类二次根式就无需再进行处理,既多余又复杂的事我们何必做呢?例2(八年级上册第198页)以绳测井,若将绳三折测之,绳多五尺;若将绳四折测之,绳多一尺.绳长进深各几何?
In the teaching process, I found that the division of mathematics textbook of Beijing Normal University version of the number of processing a bit cumbersome, presented for discussion. Example 1 Calculation: (1) cos60 ° + sin45 ° -tan30 ° (2) 6tan ~ 230 ° -3 ~ (1/2) sin60 ° -2cos45 ° The reference answers provided by the teacher’s book are: (1) (3 + 32 ~ (1/2) -23 ~ (1/2))) / 6 2) (1-22 ~ (1/2)) / 2 These two answers are too cumbersome, I think it is more concise to write: (1) 1/2 + 1/22 ~ (1/2) -1 / 33 ~ (1/2) (2) 1 / 2-2 ~ (1/2) In fact, not the same type of secondary root no longer need to be processed, it is both redundant and complex thing why we do it? P. 198) to log the rope, if the rope is folded in three, the rope shall be five feet in length; if the rope is folded in four, the rope shall be one foot long.