Practice Composition Chains in Math

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

A composition chain is a sequence of functions applied one after another: (fโˆ˜gโˆ˜h)(x)=f(g(h(x)))(f \circ g \circ h)(x) = f(g(h(x))), evaluated inside-out from right to left.

Work from the innermost function outward โ€” compute h(x)h(x) first, then feed that result to gg, then feed that to ff. The order matters critically.

Showing a random 20 of 50 problems.

Example 1

easy
Let f(x)=2x+1f(x) = 2x + 1 and g(x)=xโˆ’4g(x) = x - 4. Write the formula for (gโˆ˜f)(x)(g \circ f)(x).

Example 2

easy
If f(x)=2xf(x) = 2x and g(x)=x+3g(x) = x + 3, write the formula for f(g(x))f(g(x)).

Example 3

easy
Given f(x)=3xโˆ’1f(x)=3x-1 and g(x)=x2g(x)=x^2, find (fโˆ˜g)(x)(f\circ g)(x) and evaluate it at x=2x=2.

Example 4

medium
Given f(x)=x+2f(x) = x + 2, find (fโˆ˜f)(x)(f \circ f)(x).

Example 5

hard
Decompose H(x)=sinโก(ex2)H(x)=\sin(e^{x^2}) as a composition H=fโˆ˜gโˆ˜hH=f\circ g\circ h of three simpler functions.

Example 6

challenge
Given f(x)=x+af(x) = x + a and g(x)=bxg(x) = bx, find conditions on aa and bb so that fโˆ˜g=gโˆ˜ff \circ g = g \circ f for all xx.

Example 7

hard
If f(x)=1/xf(x) = 1/x for xโ‰ 0x \neq 0, find (fโˆ˜f)(x)(f \circ f)(x).

Example 8

easy
For f(x)=x+3f(x) = x + 3 and g(x)=4xg(x) = 4x, find g(f(2))g(f(2)).

Example 9

medium
With f(x)=x+1f(x) = x + 1 applied repeatedly, find (fโˆ˜fโˆ˜f)(x)(f \circ f \circ f)(x) (apply ff three times).

Example 10

easy
Let f(x)=x+1f(x)=x+1, g(x)=2xg(x)=2x, h(x)=x2h(x)=x^2. Compute (fโˆ˜gโˆ˜h)(3)(f\circ g\circ h)(3) step by step.

Example 11

medium
If f(x)=x2f(x) = x^2 and g(x)=3x+1g(x) = 3x + 1, find (fโˆ˜g)(x)(f \circ g)(x) and (gโˆ˜f)(x)(g \circ f)(x) as formulas.

Example 12

challenge
Decompose H(x)=(2x+5)3+1H(x) = (2x + 5)^3 + 1 into a chain f(g(h(x)))f(g(h(x))) of three simple functions and identify the application order.

Example 13

easy
If f(x)=2xf(x) = 2x and g(x)=x+3g(x) = x + 3, write the formula for g(f(x))g(f(x)) and note it differs from f(g(x))f(g(x)).

Example 14

easy
If f(x)=x+4f(x) = x + 4 and g(x)=xโˆ’4g(x) = x - 4, find (fโˆ˜g)(x)(f \circ g)(x).

Example 15

hard
Let f(x)=x+af(x) = x + a and g(x)=bxg(x) = bx. Find aa and bb so that (fโˆ˜g)(x)=2x+5(f \circ g)(x) = 2x + 5 and (gโˆ˜f)(x)=2x+10(g \circ f)(x) = 2x + 10.

Example 16

easy
Let f(x)=x2f(x) = x^2 and g(x)=x+1g(x) = x + 1. Find (gโˆ˜f)(3)(g \circ f)(3).

Example 17

medium
Let f(x)=2xโˆ’1f(x) = 2x - 1 and g(x)=(x+1)/2g(x) = (x + 1)/2. Compute (fโˆ˜g)(x)(f \circ g)(x) and (gโˆ˜f)(x)(g \circ f)(x).

Example 18

medium
Let f(x)=x2โˆ’1f(x) = x^2 - 1 and g(x)=x+1g(x) = \sqrt{x + 1}. Find (fโˆ˜g)(x)(f \circ g)(x) and state where it is defined.

Example 19

medium
Functions: h(x)=x2h(x) = x^2, g(x)=x+1g(x) = x + 1, f(x)=3xf(x) = 3x. Compute (fโˆ˜gโˆ˜h)(2)(f \circ g \circ h)(2).

Example 20

easy
For f(x)=3xf(x) = 3x and g(x)=xโˆ’6g(x) = x - 6, write the formula for f(g(x))f(g(x)).