The area of a rectangular painting is given by the trinomial x^2 + 4x - 21. What are the possible dimensions of the painting? Use factoring.

To find the dimensions of the painting, we need to factor the trinomial x^2 + 4x - 21.

x^2 + 4x - 21 can be factored as (x + 7)(x - 3).

Therefore, the dimensions of the painting are x + 7 and x - 3.

The possible dimensions of the painting are:
- Length = x + 7
- Width = x - 3