Is it a function or not a function?

Not a function

Step-by-step explanation:

Fails the vertical line test

No a circle is not a function.

Step-by-step explanation:

A function is a mapping from 1 set to another

eg, 1 to 2

3 to 4

while a circle it maps the same point to another

meaning it has more than two input/output

(if u get what i mean)

shift 4 units up, and 1 unit left.

it will translate f(x) = 3^x to g(x) = 3^(x+1) + 4