SAT SUBJECT TEST MATH LEVEL 1
Equations and Inequalities
THE GRAPHING METHOD
Systems of linear equations can also be solved graphically. To solve , graph each of the lines and find the point where the two lines intersect. The x– and y–coordinates of the point of intersection are the x and y values of the solution. If you have a graphing calculator, you can rewrite the equations as y = 3 – 2x and y = 3x – 7 and graph them. You can then trace along one of the lines to the point of intersection or use the calculator’s capability to locate the point of intersection.
Just because you have a graphing calculator, you do not have to use it. Many students can solve the preceding system of equations algebraically in less time than it takes to graph it on a calculator.
As a rule, use the graphing method only if your algebra skills are very weak.
If you do not have a graphing calculator, you can use the methods discussed in Chapter 13 to make a rough sketch.
Even if your sketch is not perfect, you will probably be able to eliminate at least three, and maybe even four, choices.