Proportionality A statement describing the relationship between the variables $x, y,$ and $z$ is given. (a) Express the statement as an equation of proportionality. (b) If $x$ is tripled and $y$ is doubled, by what factor does $z$ change? (See Example 3 .)
$z$ is directly proportional to the square of $x$ and inversely proportional to the fourth power of $y .$