试题

题目:
计算题
 (1)24+(-14)+(-16)+8            
(2)-54×2
1
4
÷(-4
1
2
)×
2
9

(3)(
2
3
-
11
12
-
14
15
)×(-60)
(4)-14-(1-0.5)×
1
3
×[2-(-3)2].
答案
解:(1)24+(-14)+(-16)+8               
=24-14-16+8                                      
=2;

(2)-54×2
1
4
÷(-4
1
2
)×
2
9

=54×
9
4
×
2
9
×
2
9

=6;                                  

(3)(
2
3
-
11
12
-
14
15
)×(-60)
=
2
3
×(-60)-
11
12
×(-60)-
14
15
×(-60)
=-40+55+56
=71;

(4)-14-(1-0.5)×
1
3
×[2-(-3)2]
=-1-
1
2
×
1
3
×[2-9]
=1-
1
6
×(-7)
=1+
7
6

=
13
6

解:(1)24+(-14)+(-16)+8               
=24-14-16+8                                      
=2;

(2)-54×2
1
4
÷(-4
1
2
)×
2
9

=54×
9
4
×
2
9
×
2
9

=6;                                  

(3)(
2
3
-
11
12
-
14
15
)×(-60)
=
2
3
×(-60)-
11
12
×(-60)-
14
15
×(-60)
=-40+55+56
=71;

(4)-14-(1-0.5)×
1
3
×[2-(-3)2]
=-1-
1
2
×
1
3
×[2-9]
=1-
1
6
×(-7)
=1+
7
6

=
13
6
考点梳理
有理数的混合运算.
(1)先同号相加,再计算异号相加;
(2)先判定符号,再把带分数化为假分数,乘除混合运算改为连乘计算;
(3)利用乘法分配律简算;
(4)先做乘方和括号里面的计算,再算乘法,最后算减法.
此题考查有理数的混合运算: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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