已知函数f(x)=㏒2^x+1,若f(a)=1,则a等于?

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已知函数f(x)=㏒2^x+1,若f(a)=1,则a等于?
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已知函数f(x)=㏒2^x+1,若f(a)=1,则a等于?
已知函数f(x)=㏒2^x+1,若f(a)=1,则a等于?

已知函数f(x)=㏒2^x+1,若f(a)=1,则a等于?
没有括号就是令人疑惑的.三种情况
f(x) = log(2^x + 1)
f(a) = 1
log(2^a + 1) = 1
2^a + 1 = 10
2^a = 9
a * log2 = log9 = 2log3
a = 2log3/log2
f(x) = log(2^x) + 1 = xlog2 + 1
alog2 + 1 = 1
a = 0
f(x) = log[2^(x + 1)] = (x + 1)log2
(a + 1)log2 = 1
alog2 = 1 - log2
a = 1/log2 - 1

a=0