I have 3 problems I'm struggling with. Any help would be great

1) Given the function below

f(x)=100x3+253
-Find the equation of the tangent line to the graph of the function at

x=1. Answer in

mx+b form.

(Now, I found the derivative (100x^2)/(100x^3+25)^2/3. I then plugged 1 in as x and got 4, and when putting it into the point-slope form equation, I get 4x. But for some reason, the test I'm taking is telling me this is wrong, so I'm stumped already.)

The rest goes..

-Use the tangent line to approximate

f(1.1).

-Compute the actual value of

f(1.1). What is the error between the function value and the linear approximation?

Answer as a

__positive value only.__ Approximate to 5 decimal places.