What did happen with my list?

Question

a=[2,4,6,8]
b=a
b[0]=7
a[3]=9
b.append(5)
print (a)
Why have i got [7,4,6,9,5]?

Answer 1

a and b are identical (because of a=b line) and each operation on one of them will apply to another.

b [0]=7 => a [0]=7
a [3]=9 => b [3]=9
b.append (5) => b [4]=5 => a [4]=5

And finally:
a=[7,4,6,9,5]

Answer 2

https://www.sololearn.com/learn/JUMP_LINK__&&__Python__&&__JUMP_LINK/2431/