Answer:
a) a^6+6a^4b+15a^2b^2+20b^3+15(b^4/a^2)+6(b^5/a^4)+(b/a)^6
b) 20
c) a^6+6a^4+15a^2+20+15/a^2+6/a^4+1/a^6
Step-by-step explanation:
(a+b/a)^6=a^6+6a^5(b/a)+15a^4(b/a)^2+20a^3(b/a)^3+15a^2(b/a)^4+6a(b/a)^5+(b/a)^6
a^6+6a^4b+15a^2b^2+20b^3+15(b^4/a^2)+6(b^5/a^4)+(b/a)^6
b) the coefficient of b^3=20
c) if b=1, the expression is
a^6+6a^4+15a^2+20+15/a^2+6/a^4+1/a^6
