Two Letters
Part of the Expressions & Data section of Coddy's Pre-Algebra journey. Lesson 19 of 52.
An expression can hold more than one letter. In 3x + 2y + x - 5y, the x terms are like each other and the y terms are like each other, but an x term and a y term are unlike. Collect each letter on its own.
The x terms are 3x + x, which is 4x. The y terms are 2y - 5y, which is -3y. So the expression simplifies to 4x - 3y, and that is as far as it goes.
Why stop there? x and y can be different numbers, so 4x - 3y has no single number of anything to combine into. It is like adding 4 metres to 3 kilograms: two quantities, written side by side.
Challenge
Simplify 2a + 3b - a + 4b 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