X4 + y4 – 2x2y2)As we know,⇒ x2 + y2 – 2XY = (x – y)2⇒ √(x2 – y2)2 = x2 – y2 = (x – y)(x + y)\(\Rightarrow \left( {{\rm{a}} + {\rm{\;}}\FRAC{1}{{\rm{a}}} - {\rm{a\;}} + {\rm{\;}}\frac{1}{{\rm{a}}}} \right)\left( {{\rm{a\;}} + {\rm{\;}}\frac{1}{{\rm{a}}}{\rm{\;}} + {\rm{\;a}} - \frac{1}{{\rm{a}}}} \right)\)⇒ [2/a] × 2a⇒ 4