Factor this expression completely
9a4 - b2
(3a^2 -b)(3a^2 + b)
= (a sqrt3 -sqrtb)(a sqrt3 + sqrtb)(3a^2 + b)
To factor the expression 9a^4 - b^2 completely, we need to look for common factors and apply appropriate factoring techniques if needed.
Step 1: Identify if there are any common factors in both terms of the expression. In this case, there are no common factors between 9a^4 and -b^2.
Step 2: Check if the expression is a difference of squares. A difference of squares can be factored as the product of the sum and difference of the square roots of the terms. However, 9a^4 - b^2 is not a difference of squares because the first term is not a perfect square.
Step 3: The expression cannot be factored further since there are no common factors and it is not a difference of squares. Thus, 9a^4 - b^2 is the factored form of the expression.