Linearization problems... very confused:(

Here are some problems I have in a review test tomorrow.

Which of the following is an equation of the line tangent to the graph of f(x) = x^6 - x^4 at the point where f'(x) = -1

Consider the function f(x) -sin(kx) + 3 Given that F' (0) = k, what is the approximate value of f(0.03)

Consider the function f(x) = aln(x+2). Given that f'(1)= a/3 what is the approximate value of f(0.98)

I know for easier problems you use y - y1 = m(x-x1)

but for these problems you are missing x i think.. right?

I am so confused :(

I would really appreciate it if someone guided me the right way... thank you!