Question

已知x,y为自然数,试求最大的y值,使得存在唯一的x满足不等式 9/17 < x/x+y < 8/15

Answer 1

9/17 < x/(x+y) < 8/15可以看成一个方程组：

9/17 < x/(x+y)

x/(x+y) < 8/15

9/17 < x/(x+y) =>x+y>x*17/9 =>y>8x/9 =>y>64x/72

x/(x+y) < 8/15 =>x+yyy