The graph of a function can be vertically stretched or shrunk by multiplying the function rule by a positive number $a.$ The vertical distance between the graph and the $x\text{-}$axis will then change by the factor $a$ at every point on the graph. If $a>1,$ this will lead to the graph being stretched vertically. Similarly, $a<1$ leads to the graph being shrunk vertically. Note that $x\text{-}$intercepts have the function value $0.$ Therefore, they are not affected by this transformation. The general form of this transformation is shown in the table.

Transformations of $f(x)$
Vertical Stretch or Shrink	Vertical stretch, $a>1$ $y=af(x)$
	Vertical shrink, $0<a<1$ $y=af(x)$