In the last chapter, we showed you how to solve these—a necessary skill if there are no answer choices to
plug in. Here, PITA is definitely the way to go. Start by plugging in the value given for k, which is 3. The
equation becomes = 3 – x.
Now pick a value for x from the answer choices and plug it into the equation to see if it works. Rather
than starting with a specific answer choice, start with a number that appears more than once in the
answers, such as x = 2. The equation becomes = 3 – 2, then = 1, and 1 = 1. That’s true,
so eliminate (A) and (D), which don’t include 2.
Try it again with x = 6 to see if the correct answer is (B) or (C). You get 3 – 6 or .
This doesn’t work, so eliminate (C) and choose (B).
PLUGGING IN YOUR OWN NUMBERS
Plugging In the Answers enables you to find the answer to problems whose answer choices are all
numbers. What about problems that have answer choices containing variables? On these problems, you
will usually be able to find the answer by Plugging In your own numbers.
Plugging In is easy. It has three steps:- Pick numbers for the variables in the problem.
- Use your numbers to find an answer to the problem. Circle your answer.
- Plug your numbers from Step 1 into the answer choices to see which choice equals the
answer you found in Step 2.
The Basics of Plugging In Your Own Numbers
This sort of Plugging In is simple to understand. Here’s an example:
13.Which of the following is equivalent to the expression ?