Question

Any line with no slope is parallel to the
x-axis
y axis
line y=x

Answer 1

A line with no slope will be parallel to the y-axis, because a line with a slope of undefined means that the x-ordinates do not change in relation to the y-ordinates.
By using the gradient formula,
`(y_1 - y_2)/(x_1 - x_2)`, your x₁ and x₂ will yield the same value, thus forming a zero denominator.

As such, a vertical line will always have an undefined gradient, meaning that it has no slope at all.