Hi, I'm having a serious headache here. I know about the vertical line test and x cannot be repeated. But how to tell if the equations below are a function of not without drawing a graph?

1. sin(x+y)=1

2. x + e^y = 1

3. x = (sin y)^2

4. y - x - x^(1/2) = 17

5. y = (4x - 2)/(3x - 1)

Any help is greatly appreciated. Thanks in advance.