Hope this helps?
Desmos is a great resource to help you understand the concept.
Answer: (1,4)
Explanation: The domain looks at the x coordinates and (1,4) is the only x coordinate in the range given (due to the bracket)
Simple you just solve for y and put the equation in slope-intercept form
Answer:
Its non linear because of the x squared. This would indicate an ever increasing answer, not one that has a constant rate. This equation would be quadratic.