<PRE><B>Question 338802</B>
a rectangular solid has a volume of 640 cu.units.the width is 3 units more than
 the height and the length is 1 unit more than three times the height.
 find the dimension of the solid
:
Let x = the height
then
(x+3) = width
and
(3x+1) = length
;
x(x+3)(3x+1) = 640
x(3x^2 + x + 9x + 3) = 640
x(3x^2 + 10x + 3)
3x^3 + 10x^2 + 3x - 640 = 0
:
Plot this equation, find the x intercept
{{{ graph( 300, 200, -6, 10, -700, 300, 3x^3 + 10x^2 + 3x - 640) }}}
: 
x = 5 is the height
then
5 + 3 = 8 is the width
and
3(5) + 1 = 16 is the length
:
Check: 5 * 8 * 16 = 640 cu/units
</PRE>