How do you use the tangent line approximation to approximate the value of ln(1004)ln(1004) ?

1 Answer
Oct 28, 2014

A formula for a tangent line approximation of a function f, also called linear approximation , is given by

f(x)~~f(a)+f'(a)(x-a),
which is a good approximation for x when it is close enough to a.

I'm not sure, but I think the question is about approximate the value ln(1.004). Could you verify it please? Otherwise we will need to know an approximation to ln(10).

In this case, we have f(x)=ln(x), x=1.004 and a=1.

Since,
f'(x)=1/x=>f'(1)=1 and ln(1)=0, we get

ln(1.004)~~ln(1)+1*(1.004-1)=0.004.