Using a Formula
Part of the Fundamentals section of Coddy's Math journey. Lesson 56 of 64.
A formula is an equation that stays true for every case, with letters for the quantities that vary. The perimeter of a rectangle: P = 2l + 2w. Distance at a steady speed: d = st. Area of a rectangle: A = lw.
To use a formula, substitute the values you know and work out the one you want. A rectangle 5 by 3: P = 2 × 5 + 2 × 3 = 16. With l = 5 and w = 3 written beside the formula, substitute each into it; the arithmetic then gives P.
Challenge
The distance formula d = st with s = 60 and t = 3. Find d.
Try it yourself
Solve for d,s,t
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 First