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a) We will set the inequalities
2x^2 + 9 >= 2x^2 - 1
9 >= -1
So, for any real number x, the statement is true.

b) Since x can be any real number, and 2x^2 + 9 increases as x increases for x > 0, and increases as x decreases for x < 0. We consider lim (x -> +infinity) [2x^2 + 9] = +infinity, and lim (x -> -infinity) [2x^2 + 9] = +infinity. The maximum area of the piece of land is infinite.