t
= 1/a+1/b
= 1*(1/a+1/b)
= (a+2b)*(1/a+1/b)
= 3+ 2b/a+ a/b
>= 3+ 2*根号下(2b/a* a/b)
= 3+ 2*根号2
所以:t(min)= 3+ 2*根号2
取等条件:2b/a= a/b,即:a^2= 2b^2
t
= 1/a+1/b
= 1*(1/a+1/b)
= (a+2b)*(1/a+1/b)
= 3+ 2b/a+ a/b
>= 3+ 2*根号下(2b/a* a/b)
= 3+ 2*根号2
所以:t(min)= 3+ 2*根号2
取等条件:2b/a= a/b,即:a^2= 2b^2