题目内容
(理)已知两圆⊙C1:x2+y2+D1x+E1y-3=0和⊙C2:x2+y2+D2x+E2y-3=0都经过点A(2,-1),则同时经过点(D1,E1)和点(D2,E2)的直线方程为A.2x-y+2=0 B.x-2y-2=0 C.x-2y+2=0 D.2x+y-2=0
答案：(理)A ∵⊙C1与⊙C2都过A(2,-1),
∴
即
∴过(D1,E1)和(D2,E2)的直线为2x-y+2=0.
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题目内容
(理)已知两圆⊙C1:x2+y2+D1x+E1y-3=0和⊙C2:x2+y2+D2x+E2y-3=0都经过点A(2,-1),则同时经过点(D1,E1)和点(D2,E2)的直线方程为A.2x-y+2=0 B.x-2y-2=0 C.x-2y+2=0 D.2x+y-2=0
答案：(理)A ∵⊙C1与⊙C2都过A(2,-1),
∴即
∴过(D1,E1)和(D2,E2)的直线为2x-y+2=0.