下列各题怎样算简便就怎样算.
+×÷2
[1-(+)]÷25%
×0.75+×???????????????????????
(+-)×24.
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解:+×÷2,
=+,
=+,
=,
=;
[1-(+)]÷25%,
=[1-],
=×4,
=;
×0.75+×,
=×+,
=()×,
=1×,
=;
(+-)×24,
=24+×24-24,
=18+12-14,
=16.
解析分析:+×÷2,把除以2改为乘,注意分数之间分子与分母的约分;
[1-(+)]÷25%,先算小括号内的,再算中括号内的,最后算括号外的;
×0.75+×,把0.75化成分数,或把化成小数,用乘法分配律的逆运算简算;
(+-)×24,用乘法分配律简算.
点评:此题考查了学生对运算顺序的掌握情况,以及运用所学知识灵活巧算的能力.