Question

已知log9(9右下角小写)5=a,log9(9右下角小写)7=b,求log3(3右下角小写)35.

Answer 1

log9(9右下角小写)5=a

换底：以3为底

[log3(3右下角小写)5]/[log3(3右下角小写)9]=a

[log3(3右下角小写)5]＝[log3(3右下角小写)9]*a＝2a___(1)

同理,[log3(3右下角小写)7]＝2b___(2)

(1)+(2)

[log3(3右下角小写)5]+[log3(3右下角小写)7]=2a+2b

即：

log3(3右下角小写)35＝2a+2