Having trouble with basic algebra!

Question

I need to graph 8 linear equations, but I have no idea how to do it. The first one (and I'm assuming the most simple) is y=-x-1.

 

I've found several graphing calculators online that give the answer, and show the graph, but I need to figure out how to get to that point in the simplest terms possible.

Answer 1

To graph any line, all you need is two points that lie on the line.  You can then plot those two points and use a straight edge to draw the line that passes through those two points.  Finding two points on the line is easy if you have the equation.  Just plug in any value for x into the equation and compute the corresponding y value.

 

Using your example, y = -x -1, let's try x=1:

 

y = -x - 1

y = -(1) - 1            [plugged in x = 1]

y = -2

 

So one point on the line is (1,-2).  Remember, the ordered pair (1,-2) means (x=1,y=-2).  Now pick another value of x, say x=0:

 

y = -x - 1

y = -0 - 1             [plugged in x = 0]

y = -1

 

The second point is (0,-1).  Now plot the two points (1,-2) and (0,-1) on a graph and use a straight edge to draw the line through them.  Remember that the line extends past the two points.