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`(1-x)(1+x^2)(1+x)(1+x^2)` equals:a.1-x^6b.1+x^6c.1-x^8d.1+x^8e. None of the above

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nasirjam | Student, Grade 9 | (Level 2) Honors

Posted March 6, 2013 at 9:12 PM via web

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`(1-x)(1+x^2)(1+x)(1+x^2)` equals:

a.1-x^6

b.1+x^6

c.1-x^8

d.1+x^8

e. None of the above

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degeneratecircle | High School Teacher | (Level 2) Associate Educator

Posted March 6, 2013 at 9:38 PM (Answer #1)

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None of the original answer choices is correct, so I added a choice e. We can rearrange and then use the difference of squares formula twice.

`(1-x)(1+x)(1+x^2)(1+x^2)=(1-x^2)(1+x^2)(1+x^2)`

`=(1-x^4)(1+x^2)=1+x^2-x^4-x^6.`

This is the second multiple choice question you've posted recently where all the answer choices are wrong. If you're getting them from a book, I suggest finding a new book :)

Sources:

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atyourservice | Student, Grade 10 | (Level 3) Valedictorian

Posted February 23, 2014 at 4:46 AM (Answer #2)

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based on the calculations on my paper it is e

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