X 1+2y= 17。

For X 1+2y= 1.

There is a special solution X 1=- 1, y= 1,

So for X 1+2y= 17.

There is a special solution X 1=- 17, y= 17,

So for X 1+2y= 17.

There are solutions X 1=- 17-2t, y= 17+t,

So x2+x3 =17+t.

Let X3=T

Then x2 =17+t-t.

X3=T

And because X 1=- 17-2t.

So the integer solution is

X 1= - 17-2t

X2= 17+t-T

X3=T

Integer classification

With 0 as the boundary, integers are divided into three categories:

1, a positive integer, that is, an integer greater than 0, such as 1, 2, 3…

2,0 is neither a positive integer nor a negative integer (0 is an integer).

3. Negative integers, that is, integers less than 0, such as-1, -2, -3…