f(x)= a- 2/(2的x次方+1)为奇函数
f(-x) = -f(x)
a - 2/(2的(-x)次方+1)= - [a- 2/(2的x次方+1)]
a - 2*2^x/(2的x次方+1)= - a+ 2/(2的x次方+1)
2a = 2*2^x/(2的x次方+1)+ 2/(2的x次方+1) = (2*2^x+ 2)/(2的x次方+1)= 2
a = 1
f(x)= a- 2/(2的x次方+1)为奇函数
f(-x) = -f(x)
a - 2/(2的(-x)次方+1)= - [a- 2/(2的x次方+1)]
a - 2*2^x/(2的x次方+1)= - a+ 2/(2的x次方+1)
2a = 2*2^x/(2的x次方+1)+ 2/(2的x次方+1) = (2*2^x+ 2)/(2的x次方+1)= 2
a = 1