Question 1036056
f(x) a linear function implies that f(x) = ax + b for some constants a and b.
Note that a is the slope of the line and b is the y-intercept of the line.

Now {{{f(2) = 2a + b <= 3a + b = f(3)}}}  ==> {{{0 <= a}}}.  

Also,

{{{f(4) = 4a + b >= 5a + b = f(5)}}}  ==> {{{0 >= a}}}.  

Hence {{{0 <= a}}} and  {{{0 >= a}}} ==> a = 0 ==> line has slope 0, and thus it is a horizontal line, or a "flat" line.

==> f(x) = b, and since f(6) = 10 = b, the linear function is {{{highlight(f(x) = 10)}}}.