Question

prove that if n^2 + 1 >= 2^n when n is a positive integer with 1<= n <= 4

Answer 1

plug in 1,2,3,4

Answer 2

isn't substitution forbidden in proving?

Answer 3

proof by cases...there are 4 cases...n=1,2,3,4

Answer 4

genius

Answer 5

but still....substitution is forbidden in proving.....

Answer 6

my way is correct

Answer 7

so...substitution is allowed in proving?

Answer 8

it is only forbidden to use examples if you don't exhaust all the possibilities. In the above I did all cases