MATLAB: Solve(E) gives different answers when using x and y as symbolic varible

Question

Hi,

I have run into a problem with solve(eqn,var) function.

>>solve('exp(2*x)+3*exp(x)=54')
gives me just one answer:
 >>log(6).

However, when I switch x to y.

>>solve('exp(2*y)+3*exp(y)=54')

the answers become: log(6) and log(9) + pi*1i.

Is x somehow special? I am using matlab R2016a

Answer 1

Even when you pass in a string, solve() interacts with any assumptions you have created for the symbol names. You could see that behavior if you had done

syms x real

Or

syms x positive