Question

12.求值:-|||-(1)已知 39^m27^m=3^16,

Answer 1

39^m27^m=3^16
取对数得mln39+mln27=16ln3,
m(4ln3+ln13)=16ln3,
m=16ln3/(4ln2+ln13).

Answer 2

39^m*　27^m=3^16
两边取对数
ln(39^m*　27^m)=ln3^16
ln39^m+ln27^m=ln3^16
m（ln39+ln27）=16ln3
m=（ln39+ln27）/16ln3
=ln1053/16ln3