If the area of a circle is 64 pi, then whats the circumference?

Which of the following best describes the graph below? a. it is a function, but it is not one-to-one. b. it is a one-to-one function. c. it is not a function. d. it is a many-to-one function.

Can someone factor this fully? my friend and i have two different answers and i would like to know if either of them is right. you in advance. a^2 - b^2 + 25 + 10a

Pls brainliest will be awarded if answer is correct