The given polynomial, 81x^2 - 49, is a difference of perfect squares. To factor it completely, we can use the formula a^2 - b^2 = (a + b)(a - b).
In this case, a^2 = 81x^2 and b^2 = 49. Taking the square root of both sides, we have a = 9x and b = 7.
Therefore, the value of a is 9x and the value of b is 7.
To factor the polynomial completely, we use the formula (a + b)(a - b). Substituting the values of a and b, we have:
(9x + 7)(9x - 7)
The product of the prime factors is (9x - 7)(9x + 7).
I hope this helps!