推荐回答（2个）
x²-x/4=9/4
x²-x/4+1/64=9/4+1/64=145/64
(x-1/8)²=(±√145/8)²
x-1/8=±√145/8
x=(1-√145)/8,x=(1+√145)/8
(x-3)²+(y-1)²=25
圆心C(3,1)
PC=√(1²+2²)=√5所以P在园内
弦长最小则垂直于过P的直径
所以由勾股定理
弦长=2√(r²-PC²)=4√5
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