y=4√（3-X）+5√（X-2）的最大值?

2 < x < 3
d y /d x = - 2 (3-x)^(-1/2) + 5/2 (x-2)^(-1/2) = 0
2 (3-x)^(-1/2) = 5/2 (x-2)^(-1/2)
5/2 (3-x)^(1/2) = 2 (x-2)^(1/2)
25 (3-x) = 16 (x-2)
75 - 25x = 16x -32
41 x = 107
x = 107/41
x = 2,or x = 107/41,or x =3 ,y的最大值
y= 4 ,y= 6.403124 ,y =5
X = 107/41,y = 6.403