Inputs and Outputs
Part of the Functions & Transformations section of Coddy's Algebra 2 journey. Lesson 2 of 58.
To evaluate a function, replace every x in the rule with the input, then work out the arithmetic. Take f(x) = 2x + 5 and the input 3. Replacing x gives 2(3) + 5, which is 6 + 5, so f(3) = 11.
On the board this happens in two parts. The move Use f(x) = ... does the replacing: it writes the rule again with the input in place of x. The arithmetic after that is yours. Type each next line in the box under the problem and press Enter. The board accepts a line only when its value equals the line above it.
The name of the input letter does not matter. f(x) = 2x + 5 and f(t) = 2t + 5 are the same rule, because both double the input and add 5.
Challenge
Use g(x) = 4x - 7 to work out g(5). Tap the move that uses the rule, then type the arithmetic line by 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 Functions & Transformations
4Combining Functions
Adding FunctionsSubtracting FunctionsMultiplying FunctionsAt a Single NumberRecap: Combining10Functions in Stories
Writing the RuleUsing the RuleWorking BackwardUndoing a ConversionRecap: Stories2Expressions as Inputs
A Letter as InputA Sum as InputShifting the InputSolving f(x) = kRecap: Inputs as Expressions5Composition
One Inside AnotherOrder MattersA Function of ItselfComposing RulesBreaking ApartRecap: Composition8Stretching and Flipping
Taller and FlatterFlipping OverFlip, Then ShiftReading the RuleRecap: Stretch and Flip