Inverse function

Questions :

1.Decide whether each function is 1-1 or not

1. Not one to one function .

2. One to one function .
3. One to one function .
4. Not one to one function .

2. Determine whether each graph is the  graph of a 1-1 function (using the horizontal  line test

a. One to one function .
b. Not one to one function .

3. let
$$f(x)=2x+5$$
and
$$g(x)= \frac{1}{2}x-5$$
Is ''g'' the inverse function of ''f'' ?

$$x=2y+5 \rightarrow \,y= \frac{x-5}{2}$$
g function is not the inverse of f function .

4. Let
$$f(x)=x^3-1$$
and
$$g(x)=\sqrt[3]{x+1}$$
Is g the inverse of f ?

$$x=y^3-1\; \rightarrow \; y=\sqrt[3]{x+1}$$
so g is the inverse of f

3. answer the following question :

1.
  $$f^{-1}={(-8,-2),(-1,-1),(0,0),(1,1),(8,2)}$$

2.
  $$g^{-1}={(5,-2)(2,-1)(1,0)(5,2)}$$
3.