试题

题目:
计算:
(1)(-11
1
7
)×
1
5
+(+5
1
7
)×
1
5
+(-137
1
3
)÷5+(+113
1
3
)÷5;
(2)-8-[-7+(1-
2
3
×0.6)÷(-3)].
答案
解:(1)(-11
1
7
)×
1
5
+(+5
1
7
)×
1
5
+(-137
1
3
)÷5+(+113
1
3
)÷5
=(-11
1
7
)×
1
5
+(+5
1
7
)×
1
5
+(-137
1
3
)×
1
5
+(+113
1
3
)×
1
5

=
1
5
×[(-11
1
7
)+(+5
1
7
)+(-137
1
3
)+(+113
1
3
)]
=
1
5
×[-6+(-24)]
=
1
5
×(-30)
=-6.
(2)-8-[-7+(1-
2
3
×0.6)÷(-3)]
=-8-[-7+(1-
2
3
×
3
5
)×(-
1
3
)]
=-8-[-7+(1-
2
5
)×(-
1
3
)]
=-8-[-7+
3
5
×(-
1
3
)]
=-8-(-7-
1
5

=-8+7
1
5

=-
4
5

解:(1)(-11
1
7
)×
1
5
+(+5
1
7
)×
1
5
+(-137
1
3
)÷5+(+113
1
3
)÷5
=(-11
1
7
)×
1
5
+(+5
1
7
)×
1
5
+(-137
1
3
)×
1
5
+(+113
1
3
)×
1
5

=
1
5
×[(-11
1
7
)+(+5
1
7
)+(-137
1
3
)+(+113
1
3
)]
=
1
5
×[-6+(-24)]
=
1
5
×(-30)
=-6.
(2)-8-[-7+(1-
2
3
×0.6)÷(-3)]
=-8-[-7+(1-
2
3
×
3
5
)×(-
1
3
)]
=-8-[-7+(1-
2
5
)×(-
1
3
)]
=-8-[-7+
3
5
×(-
1
3
)]
=-8-(-7-
1
5

=-8+7
1
5

=-
4
5
考点梳理
有理数的混合运算.
(1)逆用乘法分配律计算;
(2)按照有理数混合运算的顺序,先乘除最后算加减,有括号的先算括号里面的.
要正确掌握运算顺序,即乘方运算(和以后学习的开方运算)叫做三级运算;乘法和除法叫做二级运算;加法和减法叫做一级运算.在混合运算中要特别注意运算顺序:先三级,后二级,再一级;有括号的先算括号里面的;同级运算按从左到右的顺序.
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