functionA rule that assigns exactly one output to each allowed input.
You’ll leave with these skills
01Plug a number or an expression into a functionReplace every x in the function’s equation with whatever is inside the parentheses, wrapped in its own parentheses.
02Evaluate one function inside anotherWork out the inner function first, then plug its answer into the outer function.
03Tell whether a function question gives you the input or the outputCheck whether the number sits inside the parentheses after f, which makes it an input, or across the equals sign, which makes it an output.
04Check a function’s output or a composition in DesmosType each function into Desmos on its own line, then type one function inside the other with a number in the innermost parentheses to see the output.
This lesson is part of the full library
207 lessons that teach every skill the SAT tests
71Math
40Reading
24Grammar
10 full-length practice tests to build test-day stamina and confidence
A Desmos simulator to solve math questions faster
A step-by-step guide to every practice test question
The Bluebook Simulator, so test day feels familiar
A drawing for every key term, so new ideas make sense at a glance
