Suppose we use the Binomial Theorem to expand an expression

Suppose we use the Binomial Theorem to expand an expression (x+y)ⁿ, and obtain the following.

(x+y)ⁿ = 1-(8)(2) + (28)(4) - (56)(8) + (70)(16) - (56)(32) + (28)(64) - (8)(128) + 256

Identify x, y, and n, and simplify the expression completely.

Solution

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thus anwer will be (-1+2)^8=1