题目内容
计算:(1)(-9)+4+(-5)+8;
(2)-14-
| 1 |
| 6 |
(3)(
| 7 |
| 9 |
| 5 |
| 6 |
| 3 |
| 4 |
| 7 |
| 18 |
(4)(-47.65)×2
| 6 |
| 11 |
| 6 |
| 11 |
| 5 |
| 11 |
分析:(1)是有理数的加减计算题,注意符号的变化;
(2)注意运算顺序和符号,由括号要先算括号里面;
(3)运用乘法分配律的逆运算使运算简便;
(4)运用乘法分配律是运算简便.
(2)注意运算顺序和符号,由括号要先算括号里面;
(3)运用乘法分配律的逆运算使运算简便;
(4)运用乘法分配律是运算简便.
解答:解:(1)原式=-9+4-5+8
=-2;
(2)原式=-1-
×[2-9]
=-1-(-
)
=-1+
=
;
(3)原式=-(28-30+27-14)
=-11;
(4)原式=(-47.65+37.15)×2
+10.5×(-7
)
=-10.5×2
+10.5×(-7
)
=-10.5×2
-10.5×7
=-10.5×(2
+7
)
=-10.5×10
=-105.
=-2;
(2)原式=-1-
| 1 |
| 6 |
=-1-(-
| 7 |
| 6 |
=-1+
| 7 |
| 6 |
=
| 1 |
| 6 |
(3)原式=-(28-30+27-14)
=-11;
(4)原式=(-47.65+37.15)×2
| 6 |
| 11 |
| 5 |
| 11 |
=-10.5×2
| 6 |
| 11 |
| 5 |
| 11 |
=-10.5×2
| 6 |
| 11 |
| 5 |
| 11 |
=-10.5×(2
| 6 |
| 11 |
| 5 |
| 11 |
=-10.5×10
=-105.
点评:本题是有理数的混合运算题,考查了去括号,乘法运算,乘法分配律的运用及逆运用.
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