x^2+y^2+4x-2y-3=0,则x^2+y^2的最大值为

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x^2+y^2+4x-2y-3=0,则x^2+y^2的最大值为
x^2+y^2+4x-2y-3=0,则x^2+y^2的最大值为

x^2+y^2+4x-2y-3=0,则x^2+y^2的最大值为
x^2+y^2+4x-2y-3=0
(x+2)^2+(y-1)^2=8
令x+2=2√2cosa ;y-1=2√2sina
x^2+y^2
=(2-2√2cosa)^2+(1+2√2sina)^2
=4-8√2cosa+8cos^2a+1+4√2sina+8sin^2a
=5+8(sin^2a+cos^2a)-8√2cosa+4√2sina
=13-4√2(2cosa+sina)
x^2+y^2的最大值为13+4√2*√5即13+4√10

(x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知3x-4y=0,则x^2-y^2/x^2+y^2 .|x-2y-3|+|2x-y+4|=0则x=y= 2x-y/x+y=4,则4x-2y/2x+2y+3x+3y/2x-y 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 若x+y=4,则多项式1/2(x+y)+4(x-y)-3（x-y）-3/2(x+y)-x+y值是（） 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 x*x+2x+y*y-4y+5=0 x= y= 2（x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6