A^(-1) =1/a =1 :1/2 =1 *2/1 =2
b^(-1) =1/b =1 :1/5 =1 *5/1 =5
a^(-3) =1/a^3 =1 :(1/2)^3 =1 *(2/1)^3 =2^3 =8
a^(-2) =1/a² =2² =4
b^(-2) =1/b² =5² =25
b^(-3) =1/b^3 =1 :(1/5)^3 =5^3 =125
(2+5)(8 -4*5 +2*25 -125) = -609
или
=a^(-4) -b^(-4) =1/a^4 -1/b^4 =1 :(1/2)^4 - 1 :(1/5)^4 =1*2^4 - 1*5^4 =16 -625 = -609