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Section 6.1 : Exponential Functions

4. Sketch the graph of \(f\left( x \right) = {{\bf{e}}^{ - x}}\) .

Show Solution

For this problem all we need to do is recall the Transformations section from a couple of chapters ago. Using the “base” function of \(f\left( x \right) = {{\bf{e}}^x}\) the function for this part can be written as,

\[g\left( x \right) = {{\bf{e}}^{ - x}} = f\left( { - x} \right)\]

Therefore, the graph for this part is just the graph of \(f\left( x \right)\) reflected about the \(y\)-axis.

The graph of this function is shown below. The blue dashed line is the “base” function, \(f\left( x \right)\), and the red solid line is the graph for this part, \(g\left( x \right)\).

The graph of \(g\left( x \right) = {{\bf{e}}^{ - x}}\).  The blue dashed line is the “base” function \(f\left( x \right) = {{\bf{e}}^x}\) and the solid red line is \(g\left( x \right)\), which is the graph of \(f\left( x \right)\) reflected about the y-axis.  The dashed graph increases to the right while the solid graph decreases to the right, and the two cross at \(\left( {0,1} \right)\).