Limit(5*x^3+7*x^2-9*x+14,x=7);

lim (5x^3 + 7x^2 - 9x + 14) as x = 7

to do this just substitute x = 7:
5*(7^3) + 7*(7^2) - 9*7 + 14
= 2009

hope this helps~ :)