Multiple choice Expanding any expressions in brackets: (r3+s3)(r3-s3) r9-s9 r6+2rs+s6 r6-s6 r2+2rs+s2 Reveal answer Fill a bubble to check yourself C Correct answer Explanation This is a difference of squares: (a + b)(a - b) = a^2 - b^2. Here, a = r^3 and b = s^3. So, (r^3)^2 - (s^3)^2 = r^6 - s^6.