若两条直线ax+2y+6=0与x+(a﹣1)y+(a2﹣1)=0平行,则a的取值集合是( )
A:{﹣1,2}
B:{﹣1}
C:{2}
D:{23}
对于函数y=2x-1,当自变量x=2.5时,对应的函数值是( )
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