Answer:
4x, 2x+7 and x-3.
Step-by-step explanation:
The volume of the rectangular prism shaped pencil holder is given as:
[tex]8x^3 +4x^2-84x[/tex]
To determine the dimensions of the pencil holder, we factorize the given expression.
[tex]8x^3 +4x^2-84x\\=4x(2x^2+x-21)\\=4x(2x^2+7x-6x-21)\\=4x(2x^2-6x+7x-21)\\=4x(2x(x-3)+7(x-3))\\=4x(2x+7)(x-3)[/tex]
Therefore, the possible dimensions of the pencil holder are:
4x, 2x+7 and x-3.