A little algebra rearranges it to a simple linear equation:
RE = linspace(0, 50000, 500);
% Two vectors for the function
% here is my function:
% 400 = RC/(10050 + 2*RE)
RC = 400 .* (10050 + 2*RE);
figure(1)
plot(RE, RC)
grid
xlabel('RE')
ylabel('RC')