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Example: Domain & Range

Find the domain & range of the following

  1. y=2x24y=2x^2-4
1. Sketch the function:


2. Identify any maximums or minimums that could restrict the input and output values

xyMinimumNone-4MaximumNoneNone\begin{array} {|c|c|c|} \hline &x&y\\\hline\\ \text{Minimum}&\text{None}&\text{-4}\\\\\hline \\\text{Maximum}&\text{None}&\text{None}\\\\\hline \end{array}


3. Express the domain & range in interval & set notation

DomainRangeInterval Notation(,)[4,)Set Notation{xR x is any real number}{yR y4}\begin{array} {|l|c|c|}\hline \text{}&\text{Domain}&\text{Range}\\\hline\\ \text{Interval Notation}&(-\infin,\infin)&[-4,\infin)\\\\\hline\\ \text{Set Notation}&\{x\in\mathbb{R}|~x~\footnotesize{\text{is any real number\}}}&\{y\in\mathbb{R}|~y\geq{-4}\}\\\\\hline \end{array}

  1. y=xy=\sqrt{x}
1. Sketch the function:


2. Identify any maximums or minimums that could restrict the input & output values

xyMinimum00MaximumNoneNone\begin{array} {|c|c|c|} \hline &x&y\\\hline\\ \text{Minimum}&0&0\\\\\hline \\\text{Maximum}&\text{None}&\text{None}\\\\\hline \end{array}


3. Express the domain & range in interval & set notation

DomainRangeInterval Notation[0,)[0,)Set Notation{xR x0}{yR y0}\begin{array} {|l|c|c|}\hline \text{}&\text{Domain}&\text{Range}\\\hline\\ \text{Interval Notation}&[0,\infin)&[0,\infin)\\\\\hline\\ \text{Set Notation}&\{x\in\mathbb{R}|~x\geq{0}\}&\{y\in\mathbb{R}|~y\geq{0}\}\\\\\hline \end{array}
Find the range of y=2x2+5y=-2x^2+5.
Match the first two functions with their domain, and the second two function with their range.
A.
(,4](-\infin,-4]
B.
{yR y is all real numbers}\{y\in\mathbb{R}|~y~{\footnotesize\text{is all real numbers}}\}
C.
[1,)[1,\infin)
D.
[0,)[0, \infin)
y=x+1y=\sqrt{x}+1
y=x1y=\sqrt{x-1}
y=5x+1y=5x+1
y=x24y=-x^2-4

Practice: Domain & Range

Find the domain & range of the following function shown below:


Extra Practice