<PRE><B>Question 617437</B>
1. if a box is to be 2 feet high, and the width is to be three feet less than its length. If it needs to hold a volume of 80 cubic feet, find the length and width of the box. 
Please help and show me how to solve this! I need an answer ASAP!! 
Thanks!


Volume of a rectangular prism (box) = length * width * height


Let length be L
Then width = L - 3
Height = 2


We now have: Volume = length * width * height, OR
80 = L(L - 3)(2)


80 = 2L(L - 3)


{{{80 = 2L^2 - 6L}}}


{{{2(40) = 2(L^2 - 3L)}}} ------ Factoring out GCF, 2


{{{40 = L^2 - 3L}}}


{{{L^2 - 3L - 40 = 0}}}


(L - 8)(L + 5) = 0


L, or length = {{{highlight_green(8)}}}, or L = - 5 (ignore as measurement CANNOT be negative).


Since length = 8, then width = 8 - 3, or {{{highlight_green(5)}}}

 
Send comments and “thank-yous” to “D” at  MathMadEzy@aol.com</PRE>