问题 选择题 y=x在点A(1,1)处的切线方程是( )A.x-2y+1=0B.2x-y-1=0C.x+2y-3=0D.2x+y-3=0 答案 由题意得,y′=12x,∴在点A(1,1)处的切线斜率是12,则在点A(1,1)处的切线方程为y-1=12(x-1),即x-2y+1=0,故选A.