solveEqn =
% exit pressure low
syms Pe
A_ratio = 2.06265092035577;
k = 1.1876;
Pc = 3447378.65;
eqn = ((k+1)/2)^(1/(k+1))*(Pe/Pc)^(1/k)*sqrt((k+1)/(k-1))*(1-(Pe/Pc)^(k-1)/k) == A_ratio;
solveEqn = vpa(real(vpasolve(eqn, Pe)),8)
% check the equation you typed in Matlab with actual equation
% exit pressure high (undesirable)
eqn = ((k+1)/2)^(1/(k+1))*(Pe/Pc)^(1/k)*sqrt(((k+1)/(k-1))*(1-(Pe/Pc)^(k-1)/k)) == A_ratio;
solveEqn = vpa(real(vpasolve(eqn, Pe)),8)