Gathering the x's
Part of the Fundamentals section of Coddy's Algebra journey. Lesson 30 of 64.
In 4x + 3 = x + 15, there is an x-term on both sides and a number on both sides. Collect the x-terms first by subtracting x from both sides. Then collect the numbers by subtracting 3 from both sides. Then divide.
3x + 3 = 15
3x = 12
x = 4
Check: 4 × 4 + 3 = 19 and 4 + 15 = 19.
You can collect the x-terms on either side. If you collect them on the side with the larger coefficient, the new coefficient is positive. Here the larger coefficient is on the left, so subtract x from both sides to collect the x-terms on the left.
Challenge
MediumSolve 5x + 2 = 2x + 17 for x.
Try it yourself
Solve for x
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Fundamentals
1What an Equation Is
The EquationFinding the UnknownThe Same to Both SidesSolved Means AloneRecap: First Equations4Two-Step Equations
Two Layers to UndoSubtract, Then DivideAdd, Then DivideA Division InsideNegatives in Two StepsRecap: Two-Step Equations2One-Step Equations
Undoing AdditionUndoing SubtractionUndoing MultiplicationUndoing DivisionInverse OperationsRecap: One-Step Equations5Tidying First
Like TermsTerms and Numbers MixedThe Distributive PropertyDistributing a SubtractionTidy, Then SolveRecap: Tidying First6Variables on Both Sides
x on Both SidesGathering the x'sNumbers and x's EverywhereParentheses on One SideWhen x Is NegativeRecap: Both Sides