9) log(5) 24=log(5) (8*3)=log(5) (2^3) +log(5) 3=3 log(5) 2 +log(5) 3=3a+b
10) lg2 *(log(2) 75 -log(2) 15 +log(2) 20)=lg2 *(log(2) (5^2 *3)-log(2) (3*5)+
+log(2) (2^2 *5))=lg2 *(2log(2) 5+log(2) 3 -log(2)3 -log(2)5+2log(2) 2+log(2)5)=
=lg2 *(2log(2) 5+2)=(log(2) 2 /log(2) 10) *(2log(2) 5 +2)=1/(log(2) 5+log(2)2)*
*(2log(2)5+2)=1/(log(2)5+1)/(2(log(2)5+1)=1/2
=