题目内容
计算下列各题.(能简算的要简算)
(1)6.65÷(2-1.05)×3.1
(2)1.5+4.25×0.8-2.4
(3)4.02×[(1-0.4)÷0.1]+5.4
(4)(4.38×5.6-3.38×5.6)×(3.5÷2.5)
(1)6.65÷(2-1.05)×3.1
(2)1.5+4.25×0.8-2.4
(3)4.02×[(1-0.4)÷0.1]+5.4
(4)(4.38×5.6-3.38×5.6)×(3.5÷2.5)
分析:(1)先算小括号里面的减法,再算括号外的除法,最后算括号外的乘法;
(2)先算乘法,再算加法,最后算减法;
(3)先算小括号里面的减法,再算中括号里面的除法,然后算括号外的乘法,最后算括号外的加法;
(4)先把第一个小括号里面的算式运算乘法分配律简算,再算算出第二个小括号里面的除法,然后算括号外的乘法.
(2)先算乘法,再算加法,最后算减法;
(3)先算小括号里面的减法,再算中括号里面的除法,然后算括号外的乘法,最后算括号外的加法;
(4)先把第一个小括号里面的算式运算乘法分配律简算,再算算出第二个小括号里面的除法,然后算括号外的乘法.
解答:解:(1)6.65÷(2-1.05)×3.1,
=6.65÷0.95×3.1,
=7×3.1,
=21.7;
(2)1.5+4.25×0.8-2.4,
=1.5+3.4-2.4,
=4.9-2.4,
=2.5;
(3)4.02×[(1-0.4)÷0.1]+5.4,
=4.02×[0.6÷0.1]+5.4,
=4.02×6+5.4,
=24.12+5.4,
=29.52;
(4)(4.38×5.6-3.38×5.6)×(3.5÷2.5),
=[(4.38-3.38)×5.6]×(3.5÷2.5),
=(1×5.6)×(3.5÷2.5),
=5.6×1.4,
=7.84.
=6.65÷0.95×3.1,
=7×3.1,
=21.7;
(2)1.5+4.25×0.8-2.4,
=1.5+3.4-2.4,
=4.9-2.4,
=2.5;
(3)4.02×[(1-0.4)÷0.1]+5.4,
=4.02×[0.6÷0.1]+5.4,
=4.02×6+5.4,
=24.12+5.4,
=29.52;
(4)(4.38×5.6-3.38×5.6)×(3.5÷2.5),
=[(4.38-3.38)×5.6]×(3.5÷2.5),
=(1×5.6)×(3.5÷2.5),
=5.6×1.4,
=7.84.
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.

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