# How to Check an Answer to an Algebra Problem

It is very important to check your answer to an algebra problem, as this allows you to be 100% sure that your answer to the problem is correct. Checking your answer is a relatively simple process.

### Part 1 Understanding the Basics

1. 1
Determine the variables you are working with. In every algebra problem we are asked to find the missing value of a certain x or y (whatever is used as the variable) in terms of whatever the main problem is.
• In a weight problem, we are asked to determine the weight, therefore weight must be in terms of kilograms, grams, tons etc.
• If the problem speaks of time, then the term we must be looking for should be in hours and so on, depending on what unit of quantity the problem states.
• Therefore, you have to look for the logic of the problem and see if the answer you arrive at is applicable to the terms or unit outlined in the question
2. 2
Know that you must decide if the answer you arrived at works with the equation you were given. Go back to the problem and logically determine what you are being asked for. Is the value of x = c (the value of the answer of a problem) enough to answer the question what is being asked? What does the value c represent?
• Reading back, determine the unit of the quantity and ensure that it satisfies the conditions of the problem. If it does not, continue substituting values for that particular variable until you prove true the conditions of the problem.
• Once you have fully dissected each condition the problem has given you, you are ready to proceed to the next major step.
3. 3
Place the answer in the equation. Just to be safe, substitute the value of the answer into the equation or problem to ensure that it works.
• Whatever procedure or formula/equation you used to solve the problem is the same equation you should use to prove the equation true. Substitute your answer for the missing variable or term.
• Keep in mind that sometimes in a problem you will need to solve two equations before you arrive at the real answer.

### Part 2 Checking the Answer of an Example Problem

1. 1
Read over the question again. Let's use an example problem; A box of 266 ball pens consists of red, blue and black pens. There are four times as many blue as black and twice as many red as black. How many of each are there?
• Let x = the number of black
• Then 4x = the number of blue
• And 2x = the number of red
2. 2
Write out the full equation. Using the information provided in the question, form your equation; x + 4x + 2x = 266.
• When you solve this equation, you get the value x = 38. This means there are 38 black pens, therefore:
• 4x = 152 blue pens
• and 2x = 76 red pens
3. 3
Assess your formula. Go back to the formula you created from the conditions given by the problem: x + 4x+ 2x = 266.
4. 4
Plug in your determined answer. Since you found the value of x, to check your answer you should substitute or plug in this value to the variable x.
• 38 + 4(38) + 2(38) = 266
• 266 = 266
• This answer proves that you solved the algebra problem correctly.

## Article Info

Categories: Algebra