SOLUTION: the width of a box is 9 inches more than its length. the height of the box is 1 inch less than its length. if the box has a volume of 72 cubic inches, what are the dimensions of th

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: the width of a box is 9 inches more than its length. the height of the box is 1 inch less than its length. if the box has a volume of 72 cubic inches, what are the dimensions of th      Log On


   



Question 395344: the width of a box is 9 inches more than its length. the height of the box is 1 inch less than its length. if the box has a volume of 72 cubic inches, what are the dimensions of the box.
Height: x-1
Width: x+9
Length: x

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi
Letting x, (x-1)(x+9) represent the length, height and width respectively
Question states***
x(x-1)(x+9)= 72 in^3
solving for x
x^3 + 8x^2 - 9x - 72 = 0 |x = 3 is one solution found by substitution
(x-3)(x^2 + 11x + 24)= 0 |dividing (x^3 + 8x^2 - 9x - 72) by (x-3)
factoring the quadratic
(x-3)(x+3)(x+8) = 0 |tossing negative solutions out for length
x = 3
Dimensions of the box are 3in long, 2in high, 12in wide