The equations we graphed in the previous lesson are called Linear Equations. As the name infers, a linear equation is a straight line.

Linear Equation

Not A Linear Equation

An equation is linear if the variables that occur are to the first power only, there are no products of variables and no variables are in the denominator.

Ex. 1 Determine which equations are linear. Place your mouse over the equation to check your answer.

Ex. 2  Solve 2x-2y=-4. Make a table and then draw the graph of the equation. We solve this exactly the same way we did in the previous lesson. The only difference here is that we must solve for y first.

Try graphing -x+y=3 on your own. Use the points 0,1,2 and 3 for your x values. First solve for y, then fill in the table below. Make sure you leave no spaces in the answer. When you are finished, click the Mark Table button. (ie. if x=4 you would fill in 4,4+3,7,(4,7)). Graph the equation on graph paper. Then click the down arrow in the graph below and highlight -x+y=3. See if it matches your graph. When you are finished, try 4x+2y=8 or 23x-5y=20 and check them in the graph below.