Answer:
[tex]a^7-7a^6b+21a^5b^2-35a^4b^3+35a^3b^4-21a^2b^5+7ab^6-b^7[/tex]
Step-by-step explanation:
There are multiple ways of expanding a polynomial expression to a high degree. One way of doing it is to write out the problem in the multiplication form, multiply (a - b) by itself (7) times.
[tex](a-b)^7[/tex]
[tex]=(a-b)(a-b)(a-b)(a-b)(a-b)(a-b)(a-b)[/tex]
Now simplify, multiply two terms together,
[tex]=(a^2-2ab+b^2)(a^2-2ab+b^2)(a^2-2ab+b^2)(a-b)[/tex]
Repeat this process,
[tex]=(a^4-4a^3b+6a^2b^2-4ab^3+b^4)(a^3-3a^2b+3ab^2-b^3)[/tex]
Repeat this process one final time,
[tex]a^7-7a^6b+21a^5b^2-35a^4b^3+35a^3b^4-21a^2b^5+7ab^6-b^7[/tex]
