how would you factor -x^4 + 8x^2 + 9?
2009-12-01 8:46 am
i tried factoring it by completing the square and i got (x+3)(x-3) but i don't think that's right. =[
回答 (4)
2009-12-01 9:13 am
✔ 最佳答案
-x^4 + 8x^2 + 9= -(x^4 - 8x^2 - 9)
= -(x^4 + x^2 - 9x^2 - 9)
= -[(x^4 + x^2) - (9x^2 + 9)]
= -[x^2(x^2 + 1) - 9(x^2 + 1)]
= -(x^2 + 1)(x^2 - 9)
= -(x^2 + 1)(x^2 - 3^2)
= -(x^2 + 1)(x + 3)(x - 3)
2009-12-01 9:53 pm
x^4-8x^2-9
(x^2-9)(x^2+1)
(x+3)(x-3)(x^2+1)
(x^2-9)(x^2+1)
(x+3)(x-3)(x^2+1)
2009-12-01 4:58 pm
(-x^2 - 1)(x^2 - 9)
i think is right... I'm sorta tired and did this quickly without thinking so u might wanna double check... oh and i think it can be simplified more...
(x^2 - 9) can go to (x - 3)(x + 3)
and i don't think (-x^2 - 1) can be simplified more, but maybe it can... u can use the quadratic formula to check.
i think is right... I'm sorta tired and did this quickly without thinking so u might wanna double check... oh and i think it can be simplified more...
(x^2 - 9) can go to (x - 3)(x + 3)
and i don't think (-x^2 - 1) can be simplified more, but maybe it can... u can use the quadratic formula to check.
參考: Currently have an A in university calculus.
2009-12-01 4:54 pm
(1+x^2)(9-x^2)=(1+x^2)(3-x)(3+x)
God bless you.
God bless you.
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