UC知道初一！！！！
来源：百度知道 编辑：UC知道 时间：2024/05/20 03:44:39
1.若log8 9=a,log3 5=b，用a,b的式子表示 log10 2为__
2.已知奇函数f(x)和偶函数g(x)满足f(X)+g(x)=a^x-a^(-x)+2,且g(b)=a,则f(2)的值为__
2.已知奇函数f(x)和偶函数g(x)满足f(X)+g(x)=a^x-a^(-x)+2,且g(b)=a,则f(2)的值为__
1.
b * a
= log(3,5) * log(8,9)
= log(3,5) / log(9,8) = 3/2 * log(3,5) / log(3,2)
= 3/2 * log(2,5)
= 3/2 * (log(2,10) - 1)
故 log(10,2) = 3 / (2ab + 3)
2.
f(-x) + g(-x) = 1/a^x - a^x + 2
f(x) + g(x) = a^x - 1/a^x + 2
相加得
2g(x) = 4
g(x) = 2
由于 g(b) = 2，a=2
f(x) = 2^x - 2^(-x)
f(2) = 4 - 1/4 = 15/4