i used it as the sunny said above,20423153.3 m. i type this answer in my online quiz. it said wrong. Once again,i use the v which sunny get above, 1.44km/s, to get the altitude which is 20471847.13. when i type this answer. it is still wrong. once again. i use 20471847.13-20423153.3=48693.83376...
and i want to ask where i can get the mass of Mars. and after we got the v, how we can get the altitude of a geosynchronous satellite orbiting Mars. i use the equation r+h=2pi/(vT). but it is wrong.