分析:(1)先算減法,再算加法;
(2)先算除法,再算乘法;
(3)根據(jù)減法的性質(zhì)進(jìn)行簡(jiǎn)算;
(4)根據(jù)乘法分配律進(jìn)行簡(jiǎn)算;
(5)先算除法和乘法,再算減法;
(6)先算小括號(hào)里面的乘法和加法,再算減法,最后算除法;
(7)先算減法,再算乘法,再算加法,最后算除法.
解答:解:(1)3
-+1=3
+1
=5
;
(2)8
÷21×
1=
×
1=
;
(3)9.87-5
-0.125
=9.87-(5
+0.125)
=9.87-6
=3.87;
(4)4
×7+2.4×4=4
×(7
+2.4)
=4
×10
=43;
(5)3.2÷1
-×0.75=2-0.45
=1.55;
(6)(8-3.5×
)÷(
+0.25)
=(8-1.4)÷0.85
=6.6÷0.85
=
;
(7)[4.8+1
×(3
-1.5)]÷0.12
=[4.8+1
×
]÷0.12
=[4.8+2.5]÷0.12
=7.3÷0.12
=60
.
點(diǎn)評(píng):考查了運(yùn)算定律與簡(jiǎn)便運(yùn)算,四則混合運(yùn)算.注意運(yùn)算順序和運(yùn)算法則,靈活運(yùn)用所學(xué)的運(yùn)算定律簡(jiǎn)便計(jì)算.