3×7=(-3)×7=,3×(-7)=.
(-3)×(-7)=,0×7=.,0×(-7)=.
⑴(-5)×(-2)×4×(-3)的结果的符号是;
⑵的结果的符号是.
4×2=.
(-4)×2=+=(用数轴表示).
5×2=.
(-5)×2=+=.
6×2=
(-6)×2=+=.