Question

The volume of a rectangular box is found by multiplying its length, width, and height: V = lwh. A certain box has a volume of b3 + 3b2 - 4b - 12. Factor the four-term polynomial to find the dimensions of the box. Hint: Use factoring by grouping to factor the four term polynomial first.

Answer 1

length, width, and height are (b+2), (b-2), (b+3)

Explanation:

Doing what the problem statement tells you to do, you get ...

(b^3 +3b^2) -(4b +12)

= b^2(b +3) -4(b +3) . . . . . factor each pair of terms

= (b^2 -4)(b +3) . . . . . . . . . write as a product

= (b -2)(b +2)(b +3) . . . . . . use the factoring of the difference of squares

The three factors are (b-2), (b+2), and (b+3). We have no clue as to how to associate those with length, width, and height. We just know these are the dimensions of the box.

Answer 2

length, width, and height are (b+2), (b-2), (b+3)

Explanation:

Doing what the problem statement tells you to do, you get ...

(b^3 +3b^2) -(4b +12)

= b^2(b +3) -4(b +3) . . . . . factor each pair of terms

= (b^2 -4)(b +3) . . . . . . . . . write as a product

= (b -2)(b +2)(b +3) . . . . . . use the factoring of the difference of squares

The three factors are (b-2), (b+2), and (b+3). We have no clue as to how to associate those with length, width, and height. We just know these are the dimensions of the box.