dellzasaur
Factor the expression x^4+8x^220??



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Algebraic!
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x^4+8x^220 ..?

dellzasaur
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Were doing some cubic stuff in class lol

dellzasaur
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its x^4+8x^220 @Algebraic!

Algebraic!
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substitute u =x^2

mathstudent55
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Start wit a substitution to make it simpler:
Let u = x^2, then u^2 = x^4. Now re3place the x's with the u's:
u^2 + 8u  20
Can you factor that one?

dellzasaur
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@mathstudent55 Im not sure.... My teacher didnt really go over this so i have no idea. Would I pull out a 4?

Algebraic!
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u^2 + 8u  20
is a quadratic... you've factored a lot of those by now I think....

Algebraic!
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what two number multiply to give 20 and add to give 8?

dellzasaur
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@Algebraic! 10 and 2

Algebraic!
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(u+10)(u2) = (x^2 +10)(x^2 2)

Algebraic!
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(x^22) is a difference of squares.. so you can factor that ...

dellzasaur
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@Algebraic! Okay so what would i do with the other equation?

Algebraic!
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(x^2+10) ? no real roots...