Chapter 8.4A, Problem 22A

Which of the following equations or inequalities represent function and which do not? In each case, $x\text{ and }y$ are real number; $x$ is in the domain and $y$ in the range. If your answer is not a function explain why not.

a. $x+y=2$

b. $x-y<2$

c. $y=x^3+x$

d. $xy=2,x\ne 0$

e. $y=\left|x\right|$

f. $\left|y\right|=x$

g. $x^2+y^2=1$

h. $y=\sqrt{x}$