Graphing Another Equation

Let's ask Joan to graph a different line: y = 4x - 2.

Joan needs to find values for x and y that make the equation true. She decides to start by substituting 0 for x, just as before.

y = 4x - 2
y = 4 * 0 -2
y = 0 - 2
y = -2

Joan's substitution tells her the equation is true when x = 0 and y = -2, so she graphs the point (0, -2).

When an equation is written like this one, it's fairly simple to find y by substituting different values for x. Joan decides to let x = 1:

y = 4x - 2
y = 4 * 1 - 2
y = 4 - 2
y = 2

Now Joan knows that x = 1, y = 2 also works, so she graphs (1, 2).

Next, Joan crawls down the y-axis and sticks her tongue straight through the two points. The straight part of her tongue will make a green trace.

Before she leaves, Joan draws arrows to show that her line continues forever. She also labels the line with the equation it came from.

Joan just graphed y = 4x - 2.