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Section 1.10 : Common Graphs

2. Without using a graphing calculator sketch the graph of \(f\left( x \right) = \left| {x - 3} \right|\).

Show Solution

Recall the basic Algebraic transformations. If we know the graph of \(g\left( x \right)\) then the graph of \(g\left( {x + c} \right)\) is simply the graph of \(g\left( x \right)\) shifted right by \(c\) units if \(c < 0\) or shifted left by \(c\) units if \(c > 0\).

So, in our case if \(g\left( x \right) = \left| x \right|\) we can see that,

\[f\left( x \right) = \left| {x - 3} \right| = g\left( {x - 3} \right)\]

and so the graph we’re being asked to sketch is the graph of the absolute value function shifted right by 3 units.

Here is the graph of \(f\left( x \right) = \left| {x - 3} \right|\) and note that to help see the transformation we have also sketched in the graph of \(g\left( x \right) = \left| x \right|\).

The graph of \(f\left( x \right) = \left| {x - 3} \right|\), drawn as a solid red curve, along with the graph of \(g\left( x \right) = \left| x \right|\), drawn as a dashed gray curve.  Both are V shapes that open upward.  The vertex of \(g\left( x \right)\) is at the origin and the vertex of \(f\left( x \right)\) is at (3,0), so the graph of \(f\left( x \right)\) is the graph of \(g\left( x \right)\) shifted right 3 units.