Mathematics
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OpenStudy (anonymous):
Just wanted to check my answers if they are right. (See below)
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OpenStudy (anonymous):
1.)\[\frac{ x-4 }{ x^2-3x-4 }\]
OpenStudy (anonymous):
My answer: \[\frac{ 1 }{ (x+1) }\]
OpenStudy (anonymous):
1 is correct
OpenStudy (anonymous):
Thanks!
2.) \[\frac{ x^3-8 }{ x-2 }\]
OpenStudy (anonymous):
My answer:\[(x+2)^2\]
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OpenStudy (anonymous):
I think u can simplify more than that
OpenStudy (anonymous):
How would I simplify that?
OpenStudy (anonymous):
hold on
OpenStudy (anonymous):
something is wrong
OpenStudy (anonymous):
I don't think I factored the numerator right.
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OpenStudy (anonymous):
start by putting the 8 into 2^3
OpenStudy (anonymous):
Okay. Then what?
OpenStudy (anonymous):
and use the difference of cubes which is \[a^3−b^3=(a−b)(a^2+ab+b^2)\]
OpenStudy (anonymous):
it will get you \[(x−2)(x^2+(x)(2)+2^2)\]
OpenStudy (anonymous):
Simplify 2^2 to 4 and regroup terms
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OpenStudy (anonymous):
\[\frac{ (x−2)(x^2+2x+4) }{ x-2 }\]
OpenStudy (anonymous):
now just cancel the x-2
OpenStudy (anonymous):
did you get it?
OpenStudy (anonymous):
Ya I got it. Wasn't that the same answer I got?
OpenStudy (anonymous):
\[(x+2)^2\]
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OpenStudy (anonymous):
It's different
OpenStudy (anonymous):
I wrote the same answer.
OpenStudy (anonymous):
\[x^2+2x +4 \neq (x+2)^2\]
OpenStudy (anonymous):
Ya sorry about that. Just noticed.
OpenStudy (anonymous):
I would have to use the quadratic formula for this right?
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OpenStudy (zale101):
\(a^3-b^3=(x-a)(a^2+ab+b^2)\)
\(x^3-2^3=(x-2)(x^2+2x+2^2)=x^2+2x+4\)
\(\Large\frac{x^3-8}{x-2}=\frac{x^2-2^3}{x-2}=\frac{(x-2)(x^2+2x+4)}{x-2}\)
OpenStudy (zale101):
\(\Large =x^2+2x+4\)
OpenStudy (anonymous):
Ya I got that so far. Thanks!
OpenStudy (anonymous):
\[\frac{ -2\pm \sqrt{2^2-4(1)(4)} }{ 2(1) }\]\[\frac{ -2\pm \sqrt{4-16} }{ 2 }\]\[\frac{ -2\pm \sqrt{-12} }{ 2 }\]
OpenStudy (anonymous):
The answer is going to have an i?
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OpenStudy (zale101):
Yes. That's why it cant be factored. If you get complex numbers when factoring, then the polynomial is irreducible. x^2+2x+4 is a prime polynomial.
OpenStudy (anonymous):
So I don't have to simplify that then? Do I just put x^2+2x+4?
OpenStudy (zale101):
Yes :)
OpenStudy (anonymous):
Alright thanks!
3.)\[\frac{ 5-x }{ x^2-25 }\]
OpenStudy (anonymous):
My answer:\[\frac{ -1 }{ x+5 }\]
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OpenStudy (anonymous):
4.) \[\frac{ x^2-4x-32 }{ x^2-16 }\]
OpenStudy (alekos):
3 is correct
OpenStudy (anonymous):
My answer:\[\frac{ x-8 }{ x-4 }\]
OpenStudy (anonymous):
Thanks! What about #4?
OpenStudy (alekos):
yes. well done
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OpenStudy (anonymous):
Thanks you guys!