: The number of whole numbers lying between 42 and 65 is 22 (65 – 42 – 1 = 22). They are as follows 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, and 64.
You want the (positive) distance when the height is 0, 0= -d^2 + 10d +5.
You would factor that out(You'd get radicals), and the final answer would be
<span>5±<span>30<span>−−</span>√</span></span><span>
You'd take the only positive one of the two, 5 + srt(30)
I hope I did that right :/</span>