Question

已知log5 3=a log5 4=b

Answer 1

log5 3=a log5 4=b

5^a=3,5^b=4

5^(a+b)=3*4

[5^(a+b)]^2=12^2

25^(a+b)=12^2

[25^(a+b)]^(1/2)=(12^2)^(1/2)

25^[(a+b)/2]=12

所以log25 12=1/2(a+b)