When a linear function and a qudratic function are combined through addition, the result is a qudratic functiton. This statement is:

- usually true

- always true

- usually false

- always false

The sum of an even and odd function is neither even or odd. Assuming that neither function is the zero function, is this:

- always true

- sometimes true

- never true

The sum of two quadratic functions are:

- always quadratic

- always a horizontal line

- may be a quadratic function or horizontal line

- may be quadratic, linear or a horizontal line

The sum of two linear functions is:

- always a horizontal line

- may be a linear or horizontal line

- always a linear function

- always a vertical line