Let 4/x+9/y= 1.
Then x+y
=(x+y)*(4/x+9/y)
=4+9x/y+4y/x+9
≥ 13+2√[(9x/y)*(4y/x)]
= 13+2*6
=25
If and only if 9x/y=4y/x
That is, when 2y=3x, the equal sign holds.
Substitute 4/x+9/y= 1.
X= 10,y= 15。
When x = 10 and y = 15, the minimum value of x+y is 25.
∴ Fill in 10 in the first bracket and 15 in the second bracket.