A function curve $y=f(x)$ is graphed below. You can interact with the graph by sliding the endpoints of an interval along the horizontal axis and using the slider at top to change the number of rectangles, $n,$ that approximate the area under the curve.

Change the interval and rectangles, if necessary, so the graph shows the rectangular approximation given by:

${\displaystyle \underset{k=0}{\overset{7}{}}}\frac{6}{8}*f(1+k*\frac{6}{8})$