z=2设z=x+yi,x^2+y^2=4 |z-3-4i|^2=(x-3)^2+(y-4)^2=x^2-6x+9+y^2-8y+16=25+4-6x-8y=29-6x-8y设3x+4y=ux^2+(1/16)(u-3x)^2=4(25/16)x^2-(3u/8)x+u^2/16-4=0判别式(3u/8)^2-4*(25/16)(u^2/16-4)>=09u^2/64-25u^2/64+2...
