如图,直线y=2x与双曲线交于点A.将直线y=2x向右平移3个单位后,与双曲线交于点B,与x轴交于点C,若,则k= .
若a,b互为倒数,则=_______,若a,b互为相反数,=________.
用“>” “<”或“=”填空: (1)若a<0,b>0,则ab_________0; (2)若a<0,b<0,则ab_________0; (3)若a=0,b≠0,则ab_________0.
(-1)×(+2)×(-3)×(+4)×(-5)的符号是.
计算:(--+)×(-30)=______.
若|a|=5,b=-2,且ab>0,则a+b= _______.