若1/2+x+y=1（x>0,y>0),且1/x+a/y≥8恒成立,则正实数a的最小值为?求详解

若|x+y-1|+（x-y-2)²=0,求代数式（x+2y)(x-2y）-（2x-y)(-y-2x)的值. 若x+y=1,x不等于0则x+(2xy+y^2)/x/(x+y)/x= 设x大于1,y大于0,x^y+x^-y=2根号二,x^y-x^-y等于? 若x,y满足|2x-y-3|+|3x+2y+1|=0,则x= y= 若x,y满足|x-y+1|+(x+y+3)^2=0则x^2-y^2= 若|x+y+1|+(x-2y)的平方=0,则x+2y=? 若(x+y)(x+y-1)-2=0,求x+y的值求 若(2x-y-1)2+|x-2y-3|=0,求代数式(2x+y)(2x-y)-(x+2y)(x-2y-1)的值若(2x-y-1)²+|x-2y-3|=0,求代数式(2x+y)(2x-y)-(x+2y)(x-2y-1)的值 mathematica软件,已知y[x],Y=f1(x),X(x)=f2(x),如何plot Y[X]?y[x_] := x + 9.81/2*x*xk=1X[x] = x - k*y'[x]/(1 + (y'[x])^2)^0.5Y[x] = y[x] + k/(1 + (y'[x])^2)^0.5Plot[{y[x],Y[X],},{x,0,2}] 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若实数x,y满足x-y+1》=0,x+y>=0,x 若实数x,y满足x-y+1>=0,x+y>=0,x 若关于x,y的二元一次方程组x+2y=m-1,2x+y=m+1的解x,y满足x>0,y 若关于x,y的二元一次方程组x+2y=m-1,2x+y=m+1的解x,y满足x>0,y 若关于x y的二元一次方程组2x+y=2m-1 x+2y=m满足x+y>0和x-y 若X^2+Y^2+2X-6Y+10=0,先化简X+Y分之Y^2,分之X-Y分之X-1 已知x,y满足约束条件：x-y+1>=0,x+y-2>=0,x 若实数X,Y满足X²+Y²+4X-2Y +1=0,则X²-6X+Y²-2Y的最大值是多少