Perfect square trinomial: (a – b)2 = (a – b)(a – b) = a2 – 2ab + b2 Find the product of (k – 9)2 using the perfect square trinomial rule shown on the left.

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.

9.8? i'm not really sure