115.

1. Two lines, $y=\pm {\displaystyle \frac{2}{3}}x$

2. Because all of the terms on the left-hand side are nonnegative and 6 is positive, the left-hand side is always positive. Therefore, there are no x- and y-values that satisfy the equation.

3. A point, (0, 0)

4. A point, $(2,-4)$

5. Two lines, $y=\pm \sqrt{2}x$