Question

Can you explain this for me?

Answer 1

plug the values d=1,2,3,4,5 in each eq. and see where it satisfies.

Answer 2

Thank You so much, I have forgotten how to do these!

Answer 3

This is what I got for explination

Answer 4

a=6d-2
d=1
a=6*1-2=4
d=2
a=6*2-2=10
d=3
a=6*3-2=16
which is not true.
now a=5 d-1
d=1
a=5*1-1=4
d=2
a=5*2-1=9
which is not true.
again a=3 d+1
now try yourself.