1)could you please propose a suitable data structure to store above ploynomials.
2) and, how to add & multiply them using python codes.
It looks like homework. Did you try to add the polynomials in a python console ?
As Gribouilis said, there is only so much we can suggest without doing the work for you. As for data structures, there are three options I can recommend, in order from least preferred to most:
I would probably choose version two, as it probably would be the easiest for handling the arithmetic. I would wrap that representation in a
Polynomial class to make the arithmetic operations part of the whole structure.
would be ...
9*x**6 + 2*x**4 + 2*x + 5
You could store it as a string and design a little parser to pick it appart.