题目内容
用递等式计算. (1)1375+450÷18×25 | (2)168.1÷(4.3×2-0.4) |
(3)÷+= | (4)[1-(-)]× |
解:(1)1375+450÷18×25,
=1375+25×25,
=1375+625,
=2000;
(2)168.1÷(4.3×2-0.4),
=168.1÷(8.6-0.4),
=168.1÷8.2,
=20.5;
(3)÷+,
=×10+,
=+,
=;
(4)[1-(-)]×,
=[1-+]×,
=×,
=.
分析:(1)先算除法和乘法,再算加法;
(2)先算括号内的乘法,再算括号内的减法,最后算括号外的除法;
(3)先算除法,再算加法;
(4)小算小括号内的,再算中括号内的,最后算括号外的.
点评:用递等式计算,特别应注意运算顺序和运算法则.
=1375+25×25,
=1375+625,
=2000;
(2)168.1÷(4.3×2-0.4),
=168.1÷(8.6-0.4),
=168.1÷8.2,
=20.5;
(3)÷+,
=×10+,
=+,
=;
(4)[1-(-)]×,
=[1-+]×,
=×,
=.
分析:(1)先算除法和乘法,再算加法;
(2)先算括号内的乘法,再算括号内的减法,最后算括号外的除法;
(3)先算除法,再算加法;
(4)小算小括号内的,再算中括号内的,最后算括号外的.
点评:用递等式计算,特别应注意运算顺序和运算法则.
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