Another great way to solve difficult algebra questions is to use the plug and test method. Assuming that you have eliminated those choices that you know are not correct, you can use the remaining answer choices and plug them back into the original question to test which of the choices work. For example, consider the following question:
For what values of x and y is 3x2 + 2y = 14?
a. x = 0, y = 0
b. x = 1, y = 3
c. x = 1, y = 5
d. x = 2, y = 1
e. x = 2, y = 2
When you look at this question, you can rearrange the equation to be 3x2 = 14 - 2y, but that doesn't make it much easier. In fact, there are two variables in this equation, and only one equation, so there is no way to solve it exactly, but notice that the choices are all easy numbers, so just plug in and test. When x = 0 and y = 0, then the equation is 3(0) + 2(0) = 14, which is not true, so the first choice can be eliminated. Likewise, all the other choices except the fourth choice can be eliminated. When you plug in x=2 and y=1, then 3(4) + 2 = 14 is true.
 Test Tip |
The plug and test technique is a great way to arrive at the answer to an algebra question if you are stuck or if you have been able to narrow down the choices to two or three candidate answers. However, use the plug and test method only when you can use quick, easy calculations for the test part, otherwise the plug and test method will take too long and, in fact, it will be a waste of time. |