Failed to connect to MySQL: Access denied for user 'examnext_online'@'localhost' (using password: YES) Which of the following is an even function - Sarthaks eConnect

Which of the following is an even function

`f(x)=(a^x+a^(-x))/(a^x-a^(-x))`

`f(x)=(a^x+1)/(a^x-1)`

`f(x)=x(a^x-1)/(a^x+1)`

`f(x)=log_2(x+sqrt(x^2+1))`