314x≥14y≥14x y≤3143x 14y≤314

314x≥14y≥14x y≤3143x 14y≤314 证明:(y/x)+(x/y)+xy≥x+y+1 x+y)^2-14(x+y)+49 (x+y)²-14(x+y)+49 (x-y)平方-14(x+y)+49 (x-y)^2+5(x-y)-14 设变量x y满足约束条件x-y≥-1 x+y≥1 2x-y≤1 z=(x-2y)/(x+y)的最大值 x+x+x+y=20 x+x+y=14 x=?y=? 求f(x,y)=x+y+7的最大值,使(x,y)满足x+2y≤10,2x+y≥6,y≥0 {(x,y) |x|+|y| x>y?x:y 画出不等式组x+y-6≥0 x-y≥0 y≤3 x 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 已知x+y≤5,2x-y≥4,求x+2y的最大值 f(x,x)=x f(x,y)=f(y,x) (x+y)f(x,y)=yf(x,x+y)求f(14,52) (x+y)平方-14(x+y)+49y的平方 求助314x≥14y≥14t=x^14-14x 3=x-9^14-38 求y=(x^2)+2x(x≥0) y=-x+2x(x