3.68×〔1÷(-2.09)〕×(+)+ (+)×(-)(4-3.5×)÷ 2-(11.9-8.4×) 4.97×+4.97×.
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解:(1)3.68×[1÷(-2.09)]
=3.68×[1÷(2.1-2.09)],
=3.68×[1÷0.01],
=3.68×100,
=368;
(2)×(+)+
=×+×+,
=2+3+,
=5;
(3)(+)×(-)
=×,
=;
(4)(4-3.5×)÷
=(4-)×,
=×,
=;
(5)2-(11.9-8.4×)
=2-(11.9-11.2),
=2-0.7,
=1.3;
(6)4.97×+4.97×
=4.97×(+),
=4.97×1,
=4.97.
解析分析:算式(1)(3)(4)(5)根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的;
算式(2)(6)可根据乘法分配律进行计算.
点评:完成本题要细心,注意通分约分及小数、分数之间的互化.