Question

(文)若直线2ax-by+2=0(a＞0,b＞0)始终平分圆x²+y²+2x-4y+1=0的面积,则+的最小值为

A.2                B.4                 C.              D.

Answer 1

答案： (文)B  ∵2ax-by+2=0(a＞0,b＞0)始终平分圆x²+y²+2x-4y+1=0,∴直线过圆心(-1,2),即-2a-2b+2=0,a+b=1.∴≥4.