for this problem, can you use either equations?

f(x)-f(c)

x-c

or

m= (y1-y2)/(x1-x2)

or

f(b)-f(a)/b-a

anyway the question is compute the average rate of change of function f(x)=1/x-2 on (0,1)= x: x is greater than or equal to 0 and less than or equal to 1.

And find the instantaneous rate of change of f at x=0 and x=1