SOLUTION: (x^9+x^8)(x^9+x^8-x^7)

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Question 255505: (x^9+x^8)(x^9+x^8-x^7)
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
multiply x^9 by the three terms
x^9*x^9+x^9*x^8-x^9*x^7
multiply x^8 by the three terms
x^8*x^9+x^8*x^8-x^*8*x^7

x^9*x^9+x^9*x^8-x^9*x^7+x^8*x^9+x^8*x^8-x^*8*x^7
now combine like terms
x^18+x^17-x^16+x^17+x^16-x^15
x^18+2x^17-x^15 or
factored x^15(x^3+2x^2-1)