The dimensions of the poster are given as (x^2 - 6) inches by (x^2 + 12) inches.
The area of the poster is given by the product of these two dimensions:
Area = (x^2 - 6) inches * (x^2 + 12) inches
Area = x^4 - 6x^2 + 12x^2 - 72
Area = x^4 + 6x^2 - 72 inches^2
So, the area of the poster is x^4 + 6x^2 - 72 inches^2.