01 76 38 08 47
Kartable logo
HomeBrowseSearchLog in

To enjoy 10 free documents.

Kartable logo
HomeBrowseSearchLog in

To enjoy 10 free documents.

  1. Home
  2. 12th grade
  3. Precalculus
  4. Exercise : Compose two functions

Compose two functions Precalculus

Let f be the function defined by f\left(x\right)=3x^2+2x-4 and let g be the function defined by g\left(x\right)=3-2x.

Determine \left(g \circ f\right)\left(x\right).

If f and g are two functions, then the composition of these functions g\circ f is:

\left(g\circ f\right)\left(x\right)=g\left(f\left(x\right)\right)

Here:

\left(g\circ f\right)\left(x\right)=g\left(f\left(x\right)\right)=3-2\cdot f\left(x\right)=3-2\left(3x^{2}+2x-4\right)=3-6x^{2}-4x+8=-6x^{2}-4x+11

\left(g \circ f\right)\left(x\right)=-6x^2-4x+11

Let f be the function defined by f\left(x\right)=2\sqrt{x^{2}+5x-6} and let g be the function defined by g\left(x\right)=3x-2.

Determine \left(f \circ g\right)\left(x\right).

If f and g are two functions, then the composition of these functions f\circ g is:

\left(f\circ g\right)\left(x\right)=f\left(g\left(x\right)\right)

Here:

\left(f\circ g\right)\left(x\right)=f\left(g\left(x\right)\right)

\left(f\circ g\right)\left(x\right)=2\sqrt{\left(g\left(x\right)\right)^{2}+5 g\left(x\right)-6}

\left(f\circ g\right)\left(x\right)=2\sqrt{\left(3x-2\right)^{2}+5\left(3x-2\right)-6}

\left(f\circ g\right)\left(x\right)=2\sqrt{9x^{2}-12x+4+15x-10-6}

\left(f\circ g\right)\left(x\right)=2\sqrt{9x^{2}+3x-12}

\left(f\circ g\right)\left(x\right)=2\sqrt{9x^{2}+3x-12}

Let f be the function defined by f\left(x\right)=\dfrac{x-3}{x+1} and let g be the function defined by g\left(x\right)=\dfrac{2x+5}{x-6}.

Determine \left(f \circ g\right)\left(x\right).

If f and g are two functions, then the composition of these functions f\circ g is:

\left(f\circ g\right)\left(x\right)=f\left(g\left(x\right)\right)

Here:

\left(f\circ g\right)\left(x\right)=f\left(g\left(x\right)\right)=\dfrac{g\left(x\right)-3}{g\left(x\right)+1}=\dfrac{\dfrac{2x+5}{x-6}-3}{\dfrac{2x+5}{x-6}+1}=\dfrac{-x+23}{3x-1}

\left(f\circ g\right)\left(x\right)=\dfrac{-x+23}{3x-1}

Let f be the function defined by f\left(x\right)=4x^{2}-5x+6 and let g be the function defined by g\left(x\right)=x+2.

Determine \left(f \circ g\right)\left(x\right).

If f and g are two functions, then the composition of these functions f\circ g is:

\left(f\circ g\right)\left(x\right)=f\left(g\left(x\right)\right)

Here:

\left(f\circ g\right)\left(x\right)=f\left(g\left(x\right)\right)=4\left(g\left(x\right)\right)^{2}-5 g\left(x\right)+6

\left(f\circ g\right)\left(x\right)=4\left(x+2\right)^{2}-5\left(x+2\right)+6

\left(f\circ g\right)\left(x\right)=4\left(x^{2}+4x+4\right)-5x-10+6=4x^{2}+11x+12

\left(f\circ g\right)\left(x\right)=4x^{2}+11x+12

Let f be the function defined by f\left(x\right)=2x+1 and let g be the function defined by g\left(x\right)=x^{3}+4x+1.

Determine \left(g \circ f\right)\left(x\right).

If f and g are two functions, then the composition of these functions g\circ f is:

\left(g\circ f\right)\left(x\right)=g\left(f\left(x\right)\right)

Here:

\left(g\circ f\right)\left(x\right)=g\left(f\left(x\right)\right)=\left(f\left(x\right)\right)^{3}+4f\left(x\right)+1

\left(g\circ f\right)\left(x\right)=\left(2x+1\right)^{3}+4\left(2x+1\right)+1

\left(g\circ f\right)\left(x\right)=8x^{3}+12x^{2}+6x+1+8x+4+1

\left(g\circ f\right)\left(x\right)=8x^{3}+12x^{2}+14x+6

\left(g\circ f\right)\left(x\right)=8x^{3}+12x^{2}+14x+6

Let f be the function defined by f\left(x\right)=\ln\left(x\right) and let g be the function defined by g\left(x\right)=e^{2x}+3e^{x}+4.

Determine \left(g \circ f\right)\left(x\right).

If f and g are two functions, then the composition of these functions g\circ f is:

\left(g\circ f\right)\left(x\right)=g\left(f\left(x\right)\right)

Here:

\left(g\circ f\right)\left(x\right)=g\left(f\left(x\right)\right)=e^{2f\left(x\right)}+3e^{f\left(x\right)}+4=e^{2\ln\left(x\right)}+3e^{\ln\left(x\right)}+4=x^{2}+3x+4

\left(g\circ f\right)\left(x\right)=x^{2}+3x+4

Let f be the function defined by f\left(x\right)=\dfrac{2x+7}{3x-5} and let g be the function defined by g\left(x\right)=9x-1.

Determine \left(f \circ g\right)\left(x\right).

If f and g are two functions, then the composition of these functions f\circ g is:

\left(f\circ g\right)\left(x\right)=f\left(g\left(x\right)\right)

Here:

\left(f\circ g\right)\left(x\right)=f\left(g\left(x\right)\right)=\dfrac{2 g\left(x\right)+7}{3 g\left(x\right)-5}=\dfrac{2\left(9x-1\right)+7}{3\left(9x-1\right)-5}=\dfrac{18x+5}{27x-8}

\left(f\circ g\right)\left(x\right)=\dfrac{18x+5}{27x-8}

The editorial charter guarantees the compliance of the content with the official National Education curricula. Learn more

The courses and exercises are written by the Kartable editorial team, made up of teachers certified and accredited. Learn more

See also
  • Course : Relations and functions
  • Exercise : Determine cartesian coordinates of points of the plan
  • Exercise : Determine the domain and range of a function defined by a graph
  • Exercise : Add and subtract functions defined by equations
  • Exercise : Calculate the average rate of change of a function between two points using the equation of the function
  • Exercise : Find the x- and y- intercept of a function defined by a graph
  • Exercise : Find the inverse of a function
  • support@kartable.com
  • Legal notice

© Kartable 2026