# How do you graph y=-1/2 using intercepts?

Sep 3, 2016

see explanation.

#### Explanation:

It helps if we can recognise that lines of the form $\textcolor{b l u e}{\text{ y=c and x = c}}$ where c is a constant, are special cases of the equation of a straight line.

y = c is a straight line, parallel to the x-axis passing through all points in the plane with the same y-coordinate.

$y = - \frac{1}{2}$ therefore passes through all points whose y- coordinate is $- \frac{1}{2}$ This includes the point on the y-axis, the y-intercept whose coordinates are $\left(0 , - \frac{1}{2}\right)$

Plotting 3/4 points and drawing a straight line through them gives the graph of $y = - \frac{1}{2}$

For example plot the following set of points.

$\left(- 2 , - \frac{1}{2}\right) , \left(0 , - \frac{1}{2}\right) , \left(2 , - \frac{1}{2}\right) \text{ and } \left(4 , - \frac{1}{2}\right)$
graph{y-0.001x+1/2=0 [-10, 10, -5, 5]}

I mentioned x = c , which is a line parallel to the y-axis, passing through all points in the plane with the same value of x-coordinate.