Patrick B. answered • 3d

Math and computer tutor/teacher

The function is a line, so it's derivative is a fixed constant.

the domain is all reals

f(x+h) = m(x+h) + n = mx + mh + n

f(x+h) - f(x) = mx + mh + n - mx - n = mh

dividing by h gives a difference quotient of just m

the limit as h tends to zero does not change anything.

the derivative is m, the slope of the line