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  1. Home
  2. 12th grade
  3. Precalculus
  4. Exercise : Calculate expressions involving absolute values

Calculate expressions involving absolute values Precalculus

Let f be the function defined as f\left(x\right)=\left| 2x- 4\right|.

What is f\left(3\right) ?

Plug in 3 for x. We get:

f\left(3\right) = |2\left(3\right) - 4| = |6-4| = 2

f\left(3\right)=2

Let f be the function defined as f\left(x\right)=\left| x^2+4x+3\right|.

What is f\left(-1\right) ?

Plug in -1 for x. We get:

f\left(-1\right) = |\left(1\right)^2+ 4\left(-1\right)+3| = |1+ \left(-4\right) + 3| = |0| = 0

f\left(-1\right)=0

Let f be the function defined as f\left(x\right)=\left| x^2- 2\right|.

What is f\left(\dfrac{1}{2}\right) ?

Plug in \dfrac{1}{2} for x. We get:

f\left(\dfrac{1}{2}\right) = |\left(\dfrac{1}{2}\right)^2 - 2| = |\dfrac{1}{4} - 2| = |\dfrac{1-8}{4}| = |-\dfrac{7}{4}| = \dfrac{7}{4}

f\left(\dfrac{1}{2}\right) = \dfrac{7}{4}

Let f be the function defined as f\left(x\right)=\left| x^3- 8\right|.

What is f\left(-2\right) ?

Plug in 3 for x. We get:

f\left(-2\right) = |\left(-2\right)^3 - 8| = |-8-8| = |-16| =16

f\left(-2\right)=16

Let f be the function defined as f\left(x\right)=\dfrac{\left| x+1\right|}{|x^2-2|}.

What is f\left(1\right) ?

Plug in 1 for x. We get:

f\left(1\right)=\dfrac{\left| \left(1\right)+1\right|}{|\left(1\right)^2-2|} = \dfrac{\left| 2 \right|}{|-1|}= \dfrac{2}{1}=2

f\left(1\right)=2

Let f be the function defined as f\left(x\right)=\dfrac{|x^2-x-1|}{|\left(x-1/2\right)^3|}.

What is f\left(0\right) ?

Plug in 0 for x. We get:

f\left(0\right)=\dfrac{|\left(0\right)^2-\left(0\right)-1|}{|\left(0-1/2\right)^3|} = \dfrac{|-1|}{|-\left(1/2\right)^3|} = \dfrac{1}{1/8}=8

f\left(0\right)=8

Let f be the function defined as f\left(x\right)=\dfrac{x-1}{|x-1|}.

What is f\left(-\dfrac{1}{2}\right) ?

Plug in -\dfrac{1}{2} for x. We get:

f\left(-\dfrac{1}{2}\right)=\dfrac{-1/2-1}{|- 1/2-1|}= \dfrac{-3/2}{|-3/2|}= \dfrac{-3/2}{3/2}=-1

f\left(-\dfrac{1}{2}\right)=-1

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See also
  • Course : Absolute value function
  • Exercise : Graph functions involving absolute values
  • Exercise : Solve equations involving absolute values with calculations
  • Exercise : Solve inequalities involving absolute values with calculations
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