题目内容
用递等式计算 (1)1+0.45÷0.9-0.75 | (2)(5.8-3.8÷4)×0.8 |
(3) | (4). |
解:(1)1+0.45÷0.9-0.75,
=1+0.5-0.75,
=1.5-0.75,
=0.75;
(2)(5.8-3.8÷4)×0.8,
=(5.8-0.95)×0.8,
=4.85×0.8,
=3.88;
(3)×÷(-),
=,
=,
=;
(4)×[-(-)],
=,
=,
=.
分析:(1)先算除法再算加法和减法;
(2)先算括号内的除法,再算括号内的减法,最后算括号外的乘法;
(3)先算括号内的,把除法改为乘法,约分计算;
(4)先算小括号内的,再算中括号内的,最后算括号外的.
点评:此题考查了四则混合运算,注意运算顺序和运算法则.
=1+0.5-0.75,
=1.5-0.75,
=0.75;
(2)(5.8-3.8÷4)×0.8,
=(5.8-0.95)×0.8,
=4.85×0.8,
=3.88;
(3)×÷(-),
=,
=,
=;
(4)×[-(-)],
=,
=,
=.
分析:(1)先算除法再算加法和减法;
(2)先算括号内的除法,再算括号内的减法,最后算括号外的乘法;
(3)先算括号内的,把除法改为乘法,约分计算;
(4)先算小括号内的,再算中括号内的,最后算括号外的.
点评:此题考查了四则混合运算,注意运算顺序和运算法则.
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