Question -
Answer -
xy9 – yx9 = xy(y8 –x8)
= -xy(x8 – y8)
= -xy[(x4)2 – (y4)2]
= -xy (x4 + y4) (x4 – y4) {∵ a2-b2 =(a + b) (a – b)}
= -xy (x4 + y4) {(x2)2 –(y2)2}
= -xy(x4 + y4) (x2 + y2)(x2 – y2)
= -xy (x4 +y4) (x2 + y2)(x + y) (x -y)
= -xy(x – y) (x + y) (x2 + y2) (x4 +y4)