(1)(-13)×(-6)(2)-×0.15(3)(+1)×(-1)(4)3×(-1)×(-)(5)-2×4×(-1)×(-3)(6)(-2)×5×(-5)×(-2)

发布时间:2020-08-05 20:16:16

(1)(-13)×(-6)
(2)-×0.15
(3)(+1)×(-1)
(4)3×(-1)×(-)
(5)-2×4×(-1)×(-3)
(6)(-2)×5×(-5)×(-2)×(-7)

网友回答

解:(1)(-13)×(-6),
=13×6,
=78;

(2)-×0.15,
=-0.05;

(3)(+1)×(-1),
=-(×),
=-2;

(4)3×(-1)×(-),
=3×1×,
=1;

(5)-2×4×(-1)×(-3),
=-(2×4×1×3),
=-24;

(6)(-2)×5×(-5)×(-2)×(-7),
=2×5×2×5×7,
=700.
解析分析:(1)(2)(3)两个数相乘,同号得正,异号得负;
(4)(5)(6)几个不等于零的数相乘,积的符号由负因数的个数决定:当负因数有奇数个数,积为负;当负因数的个数为偶数个时,积为正.


点评:本题考查了有理数的乘法运算,①两个数相乘,同号得正,异号得负;
②几个不等于零的数相乘,积的符号由负因数的个数决定:当负因数有奇数个数,积为负;当负因数的个数为偶数个时,积为正.
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