Question

attach file question and the key,I need help
28) and 29) only
thank

Answer 1

we know |n| can be either n or -n depending whether n>=0 or n<0

so |n|>=n
n>=n or -n>=n
0>=0 or 0>=2n
so u get n<=0
~~~~~~~~~~~~~~~~~~~~~
---------------------|--------------------
0

now u can do the next..