if f (x) = mx + k find, f (x + k) - (f) x/k

Answer 1

I assume f (x + k) - f(x / k) is asked,

= m(x + k) + k - m(x / k) - k

= mx + mk - mx / k

= m{[1 + (1 / k)]x + k}

Solution 2:

if [f(x + k) - f(x)] / k is asked,

= {[m(x + k) + k] - [m(x) + k]} / k

= (mx + mk + k - mx - k) / k

= mk / k

= m