若x^2+y^2-2x-2y-3=0,则2x+y-1的最小值是?

来源：学生作业帮助网编辑：六六作业网时间：2024/11/15 20:54:38

若x^2+y^2-2x-2y-3=0,则2x+y-1的最小值是?若x^2+y^2-2x-2y-3=0,则2x+y-1的最小值是?若x^2+y^2-2x-2y-3=0,则2x+y-1的最小值是?(x-1

若x^2+y^2-2x-2y-3=0,则2x+y-1的最小值是?
若x^2+y^2-2x-2y-3=0,则2x+y-1的最小值是?

若x^2+y^2-2x-2y-3=0,则2x+y-1的最小值是?
(x-1)^2+(y-1)^2=5
令x-1=√5*cosa
x=1+√5*cosa
则(y-1)^2=5-5(cosa)^2=5(sina)^2
因为sina的值域关于原点对称
所以不妨令y-1=√5*sina
y=1+√5*cosa
2x+y-1=√5*sina+2√5*cosa+2
=√[(√5)^2+(2√5)^2]*sin(a+arctan2)+2
=5sin(a+arctan2)+2
-5

x^2+y^2-2x-2y-3=0
(x^2-2x+1)+(y^2-2y+1)-5=0
(x-1)^2+(y-1)^2=5
所以x-1>=0 y-1>=0
所以x>=1 y>=1
当x和y 都取最小值1时，2x+y-1有最小值
这时2x+y-1=2*1+1-1=2
2x+y-1最小值是2

设2x+y-1=a,y=-2x+1+a
x^2+(-2x+1+a)^2-2x-2(-2x+1+a)-3=0
x^2+4x^2-4x+1+a^2-4ax+2a-2x+4x-2-2a-3=0
5x^2-4ax-2x+a^2-4=0
判别式=(-4a-2)^2-20(a^2-4)=16a^2+16a+4-20a^2+80=-4a^2+16a+84>=0
-3<=a<=7
2x+y-1的最小值是-3

若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 若x-y不等于0,2x-3y=0,则分式(10x-11y)/(x-y)的值是（）?(10x-11y)/(x-y) =[(8x-8y)+(2x-3y)]/(x-y) =8为什么8X-8Y=8？(10x-11y)/(x-y)=[(8x-8y)+(2x-3y)]/(x-y)=8+(2x-3y)]/(x-y)=8+0=8 若2x=3y,则(x*x+y*y)/x*x=? (5)若x/2=y/3(y不为0）则x/y=____,x+y/y=___,y/x-y=___. x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 若x,y满足|x-y+1|+(x+y+3)^2=0则x^2-y^2= 若x,y满足|2x-y-3|+|3x+2y+1|=0,则x= y= 若线段x ,y 满足[2x-3y]*[3x+2y]=0 则x/y=? 若|x+y-3|+(x-y-5)^2=0,则x)^2-y^2= 若|x|=2,|y|=3,且y/2+x《0则x+y 若[x-y+3]+|2x+y|=0,则x+y=? 若3x-2y=0,则X+y/x-y等于多少? 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值若x+2y分之x-y=3,则代数式x+2y分之2（x-y)-3(x-y)分之x+2y的值为若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（）若f(x+y,y/x)=x^2-y^2,则F(X,Y)= 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7