例1:若60a=3,60b=5.求121−a−b2(1−b)的值.
问题描述:
例1:若60a=3,60b=5.求12
的值. 1−a−b 2(1−b)
答
∵60a=3,60b=5
∴a=log603,b=log605,
1-b=1-log605=log6012,
1-a-b=1-log603-log605=log604,
=1−a−b 1−b
=log124,
log604
log6012
12
=121−a−b 2(1−b)
log124=12log122=2.1 2