Step-by-step explanation:
Given
The function is [tex]f(x)=x+4[/tex]
for [tex]x_2>x_1[/tex], we will check the values of [tex]f(x_1)[/tex] and [tex]f(x_2)[/tex]
Take 3 and 4
[tex]f(4)=4+4\\f(4)=8[/tex]
Similarly,
[tex]f(3)=3+4\\f(3)=7[/tex]
Thus, [tex]f(4)>f(3)[/tex]
Also, [tex]f'(x)[/tex] is 1 i.e. a constant value. So, the function is increasing linearly for the given interval.