Factor completely 21x3y4 + 15x2y2 − 12xy3.

21x^3y^4 + 15x^2y^2 - 12xy^3

3xy^2 (7x^2y^2 + 5x - 4y) <==

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.