A ball is thrown up in the air. The table shows the height of the ball, where $x$ is the number of seconds the ball is in the air and $f(x)$ is the height (in feet) of the ball. $x$0$0.25$0.5$0.75$1.0$1.25$ $f\left(x\right)$5$12$17$20$21$20$ Write a function that models the data.
