if a = (a + a )/2 for all n greater or equal to 1. show that

a converges to (a + 2a )/3.

Please help me. I know that we want to show that the absolute value of a minus(a + 2a )/3 is less than epsilon but I am not sure how to get there. Please help.

Ok so am i supposed to know what the first few terms are? can somebody please help me?