Composition of functions

What this lesson shows

Two machines this time. Machine f adds 2. Machine g multiplies by 3. Now chain them: the output pipe of f feeds straight into g. What happens to a 2?

Try it yourself

Real questions from this lesson's worksheets — answers below each one.

1. f(x) = x² + 6. Find f(9)
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   87
2. f(x) = x + 1, g(x) = 2x. Find f(g(1))
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   3
3. True or false: f(g(x)) = g(f(x)) for every pair of functions
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   False
4. f(x) = x² + 7. Find f(6)
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   43