Derivative of limit

Question 1

What are two formulas you can use for derivatives and rate of change

Answer 1

f’(a)=limx->a f(x)-f(a)/x-a and f’(a)=x->0 f(a+h)-f(a)/h

Question 2

How do you find the equation of a tangent line with x given to you

Answer 2

First you find the slope so f’(x)=limx->0 f(x+h)-f(x)/h then finding y=mx+b