Understanding Straight Line Equations

What is the equation of a vertical line that crosses the x-axis at -7?

• y = 7

• x = 7

• y = -7

• x = -7

If a horizontal line crosses the y-axis at 5, what is its equation?

• x = 5

• y = -5

• y = 5

• x = -5

What is the equation of a line that runs along the x-axis?

• x = y

• y = 0

• y = x

• x = 0

For a diagonal line where the x-coordinate is always equal to the y-coordinate, what is the equation?

• y = -x

• x = -y

• x = y + 1

• y = x

What is the equation of a diagonal line where the y-coordinate is the negative of the x-coordinate?

• x = -y

• y = -x

• x = y

• y = x