Letters and Numbers
Part of the Expressions & Data section of Coddy's Pre-Algebra journey. Lesson 17 of 52.
3x + 7 + 5x + 1 has two kinds of terms: x terms and plain numbers. Collect each kind separately. The x terms make 3x + 5x, which is 8x, and the numbers make 7 + 1, which is 8. The result is 8x + 8.
Each term carries the sign in front of it. In 2x + 9 + 3x - 4, the last term is -4, not 4. The x terms give 5x and the numbers give 9 - 4, which is 5, so the expression is 5x + 5. Moving a term is fine because addition can be done in any order, as long as the sign travels with it.
The habit is to write the letter term first and the number last. The result has one term of each kind, and that is the simplest it gets: 8x + 8 cannot become 16x, since a plain number and a number of x's are unlike.
Challenge
Simplify 4x + 3 + 2x - 5 by combining like terms, and type the result as your next line.
Try it yourself
Simplify the expression
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Expressions & Data
1Variables and Expressions
What a Variable IsWriting ExpressionsExpressions from StoriesTwo OperationsRecap: Expressions4Combining Like Terms
Like TermsLetters and NumbersNegative TermsTwo LettersDistribute, Then CollectRecap: Like Terms2Evaluating Expressions
Substituting a ValueNegative InputsPowers in ExpressionsFormulasRecap: Evaluating5Patterns and Sequences
Continuing a PatternThe Common DifferenceThe nth TermWriting the RuleRecap: Sequences3The Distributive Property
Number PropertiesMental MathDistributing LettersDistributing a MinusRecap: Distributing