The Equation
Part of the Fundamentals section of Coddy's Math journey. Lesson 1 of 64.
An equation is a sentence in mathematics that says two things are equal. 3 + 4 = 7 is one: the left side and the right side name the same number. The equals sign is not an instruction to "work it out"; it is a claim that both sides are the same.
Most equations you will meet have a letter in them, an unknown: x + 3 = 8 says "some number, plus 3, is 8". A number that makes the sentence true is a solution. Here 5 is a solution, because 5 + 3 = 8 is true; 4 is not, because 4 + 3 = 8 is false.
An equation is solved when it has been rewritten so that the unknown stands alone on one side and its value on the other:
x = 5
That is the shape every equation in this journey is heading for. Read it as a finished sentence: "the number is 5".
Challenge
This equation is already solved: it says the number is 5.
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Try it yourself
Solve for x
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 First