①loga2+loga1/2(a>0,且a≠1) ②log3(18)-log3(2) ③1g1/4-1g25

①loga2+loga1/2=log(a)2+log(a)2^(-1)=log(a)2-log(a)2=0
②log3(18)-log3(2)=log(3)(2*9)-log(3)2=log(3)2+log(3)9-log3(2)=log(3)9=log(3)3^2=2log(3)3=2
③1g1/4-1g25=lg2^(-2)-lg5^2=-21g2-2lg5=-2*(lg2+lg5)=-2*lg(2*5)=-2lg10=-2
④ 2log5(10)+log5(0.25) =2log(5)(2*5)+log(5)(1/4)=2log(5)5+2log(5)2+log(5)1-log(5)4
=2log(5)5+2log(5)2+log(5)1-log(5)2^2=2+2log(5)2+0-2log(5)2=2
⑤2log5(25)-3log2(64)=2log(5)(5^2)-3log(2)(2^6)=4log(5)5-(3*6)log(2)2=4-18=-14
⑥log2(log2(16) =⑥log2(log(2)(2^4) )=⑥log2(4log(2)2)= log2(4)=log(2)(2^2)=2log(2)2=2