Answer:
D is true, E is true, F is true
Step-by-step explanation:
Hello,
n is an odd number it means that n = 2a+1 where a is integer
A
[tex]n^2-1=(2a+1)^2-1=4a^2+4a+1-1=4a(a+1)[/tex]
this is not an odd number
B
[tex]n(n-1)=(2a+1)2a[/tex]
this is not an odd number
C
[tex](n-1)^2=(2a+1-1)^2=4a^2[/tex]
this is not an odd number
D
[tex]n^2+2=(2a+1)^2+2=4a^2+4a+1+2=4a^2+4a+3= 2(2a^2+2a+1)+1[/tex]
so this is an odd number
E
[tex]n(n-2)=(2a+1)(2a-1)=4a^2-1=4a^2-2+1=2(2a^2-1)+1[/tex]
so this is an odd number
F
[tex](n-2)^2=(2a+1-2)^2=(2a-1)^2=4a^2-4a+1 = 2(2a^2-2a)+1[/tex]
this is an odd number
hope this helps