若log3(7)*log2(9)*log49(a)=log4(1/2),则a=?
问题描述:
若log3(7)*log2(9)*log49(a)=log4(1/2),则a=?
答
log3(7)*log2(9)*log49(a)=log4(1/2)
=lg7/lg3*2lg3/lg2*lga/2lg7=-lg2/2lg2
=lga/lg2=-lg2/2lg2
=lga=lg根号2^(-1)
a=根号2^(-1)=根号2/2