题目内容
用简便方法计算.(1)(-
| 1 |
| 4 |
(2)318×(-
| 1 |
| 9 |
(3)(0.5×3
| 2 |
| 3 |
| 3 |
| 11 |
(4)0.259×220×259×643=
分析:(1)由于162003=(42)2003=44006,再逆用同底数幂、积的乘方的运算性质,并且结合乘法的交换律、结合律简便计算;
(2)由于(-
)8=[-(
)2]8=(
)16,再逆用同底数幂、积的乘方的运算性质,并且结合乘法的交换律、结合律简便计算;
(3)先逆用同底数幂的运算性质,将(-2×
)200改写成(-2×
)199×(-2×
),再逆用积的乘方的运算性质求解;
(4)由于220=(22)10=410,643=(43)3=49,再逆用同底数幂、积的乘方的运算性质,并且结合乘法的交换律、结合律简便计算.
(2)由于(-
| 1 |
| 9 |
| 1 |
| 3 |
| 1 |
| 3 |
(3)先逆用同底数幂的运算性质,将(-2×
| 3 |
| 11 |
| 3 |
| 11 |
| 3 |
| 11 |
(4)由于220=(22)10=410,643=(43)3=49,再逆用同底数幂、积的乘方的运算性质,并且结合乘法的交换律、结合律简便计算.
解答:解:(1)(-
)4005×162003
=(-
)4005×(42)2003
=(-
)4005×44006
=(-
)4005×44005×4
=[(-
)×4]4005×4
=(-1)×4
=-4;
(2)318×(-
)8
=318×[-(
)2]8
=318×(
)16
=316+2×(
)16
=(3×
)16×32
=9;
(3)(0.5×3
)199•(-2×
)200
=(0.5×
)199•(-2×
)200
=[0.5×
×(-2)×
]199×(-2×
)
=
;
(4)0.259×220×259×643
=0.259×643×220×259
=0.259×(43)3×410×259
=(0.25×4)9×(4×25)9×4
=4×1018.
| 1 |
| 4 |
=(-
| 1 |
| 4 |
=(-
| 1 |
| 4 |
=(-
| 1 |
| 4 |
=[(-
| 1 |
| 4 |
=(-1)×4
=-4;
(2)318×(-
| 1 |
| 9 |
=318×[-(
| 1 |
| 3 |
=318×(
| 1 |
| 3 |
=316+2×(
| 1 |
| 3 |
=(3×
| 1 |
| 3 |
=9;
(3)(0.5×3
| 2 |
| 3 |
| 3 |
| 11 |
=(0.5×
| 11 |
| 3 |
| 3 |
| 11 |
=[0.5×
| 11 |
| 3 |
| 3 |
| 11 |
| 3 |
| 11 |
=
| 6 |
| 11 |
(4)0.259×220×259×643
=0.259×643×220×259
=0.259×(43)3×410×259
=(0.25×4)9×(4×25)9×4
=4×1018.
点评:解题关键是掌握同底数幂的乘法法则,同底数幂相乘,底数不变,指数相加.
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