What is a graph?

Describe what you see

\(x\)

\(y\)

Are the following points solutions to \(3x-y=1\)?

  1. \((-3, -10)\)
  2. \((-2,-7)\)
  3. \((-1, -4)\)
  4. \((0, -1)\)
  5. \((1, 2)\)
  6. \((2, 5)\)
  7. \((3, 8)\)
  8. \((0.5, 0.5)\)
  1. \((-0.5, -2.5)\)
  2. \((-1.5, -5.5)\)
  3. \((1.5, 3.5)\)
  4. \((2.5, 6.5)\)
  5. \((-2.5, -8.5)\)
  6. \((-\frac{1}{3},-2)\)
  7. \((\frac{1}{3},0)\)

The solutions all lie on the...

So the graph of a line is really...

What about the graph of things that aren't straight lines? 

To graph any straight line, plot two points on the line and connect the dots.

Why do we do that? Why does it work?

\(x\)

\(y\)

Dependent Variable always goes on the vertical axis!

Independent Variable always goes on the horizontal axis!

\(w\)

\(p\)

Which variable is the independent variable? Which one is the dependent variable?

Graph the following equations of straight lines. Be sure to clearly label axes and the points you use to plot the lines.

  • \(2x+2y=0\)
  • \(2x=2y\)
  • \(2x+3y=6\)
  • \(x=6+3y\)
  • \(3x+y=6\)
  • \(x+5y=10\)
  • \(5x-y=10\)
  • \(x=3+y\)
  • \(y=3+x\)
  • \(2y=3x-12\)