过抛物线y=1/4x^2上的点P(2,1)的切线方程为?A.x-y-1=0B.x-2y+1=0C.x+y-3=0D.2x-y=0

过抛物线y=1/4x^2上的点P(2,1)的切线方程为?A.x-y-1=0B.x-2y+1=0C.x+y-3=0D.2x-y=0
过抛物线y=1/4x^2上的点P(2,1)的切线方程为?
A.x-y-1=0
B.x-2y+1=0
C.x+y-3=0
D.2x-y=0

过抛物线y=1/4x^2上的点P(2,1)的切线方程为?A.x-y-1=0B.x-2y+1=0C.x+y-3=0D.2x-y=0
y'=x/2
x=2
y'=1
所以切线方程为
y-1=x-2
x-y-1=0
选A