解:
(1)
÷[(
)×
],
=
÷[
×
],
=
÷
,
=
;
(2)[
÷(
)-
]×
,
=[
÷
-
]×
,
=[
-
]×
,
=
×
,
=
;
(3)51.2×8.1+11×9.25+637×0.19,
=512×0.81+637×0.19+11×9.25,
=512×(1-0.19)+637×0.19+(10+1)×9.25,
=512×1-512×0.19+637×0.19+10×9.25+1×9.25,
=512+0.19×(637-512)+92.5+9.25,
=512+0.19×125+92.5+9.25,
=512+92.5+9.25+(0.2-0.01)×125,
=512+92.5+9.25+0.2×125-0.01×125,
=512+92.5+9.25+25-1.25,
=(512+25)+(9.25-1.25)+92.5,
=537+8+92.5,
=545+92.5,
=637.5;
(4)(2
+1
×5)÷3
+342
×
,
=(2
+6
)÷3
+266
,
=9
÷3
+266
,
=2
+266
,
=269.
分析:(1)先算加法,再算乘法,最后算除法;
(2)先算加法,再算除法,再算减法,最后算乘法;
(3)根据乘法分配律进行简算;
(4)先小括号里面算乘法,再算小括号里面的加法,再算除法,最后算括号外面的加法.
点评:此题主要考查分数、小数的四则混合运算的运算顺序和应用运算定律进行简便计算.