see the explanation
Step-by-step explanation:
we know that
The y-intercept is the value of the function when the value of x is equal to zero. Also is called the initial value of the function
I will analyze two cases
Part 1) we have
![f(x)=-3x](/tpl/images/0440/3146/a4b89.png)
so
For x=0
substitute
![f(0)=-3(0)=0](/tpl/images/0440/3146/c212b.png)
therefore
The y-intercept is the point (0,0)
Part 2) we have
![f(x)=-3^x](/tpl/images/0440/3146/9db64.png)
so
For x=0
substitute
![f(0)=-3^0=-1](/tpl/images/0440/3146/febd3.png)
therefore
The y-intercept is the point (0,-1)