[tex]\bf f(x)=2x\qquad \qquad f\left( \frac{2}{3}x \right)=2\left( \frac{2}{3}x \right)\implies f\left( \frac{2}{3}x \right)=\cfrac{4}{3}x
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now\quad \cfrac{4}{3}\iff 1\cfrac{1}{3}\textit{ that's smaller than }2[/tex]
f(x) = A(Bx+C)+D
any changes to A or B are vertical compressions
if you change the A from 2 to 4/3, the number is smaller than before
the smaller the A, the wider the graph, the larger the A, the more compressed the graph