I need help with these.If possible please give me a step by step guide.Thanks

1. Simplify this: ((1-(((x^-n)+(y^-n))/((x^n)-(y^-n)))^-2) )

2. Calculate:x=((a^2)+(a^-2)) and y=((a^3)+(a^-3)) If a+(a^-1)=5 (a not 0).

3. (((((a^(-2x))-(a^-x)-6))/((a^(-2x))-4)) - (((a^(-x))-1)/(2-(a^(-x)))) - 2)