What factors of -2 add to +1?
2 times -1 is -2
and 2 plus -1 is +1.
y^4 + y^2 - 2
= (y^2 -1)(y^2 +2)
y^2 - 1 is a difference of squares, so you can factor that into
(y-1)(y+1)
Answer: (y-1)(y+1)(y^2 +2)
2006-11-21 09:57:12
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answer #1
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answered by MsMath 7
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I think you mean the numbers are exponents, not variables
y^4 + y^2-2 = 0
Here's the trick: regroup the numbers to make the difference of two squares twice:
y^4 -1 + y^2-1 = 0
y^4-1 = [(y^2)^2 - 1^2]
= (y^2 -1)(y^2 +1)
Substituting these back into the original equation:
(y^2-1)(y^2+1) + (y^2-1) = 0
Taking out the common factor:
(y^2-1) [(y^2+1) + 1] = 0
Either y^2-1 = 0 => (y+1) (y-1) = 0
so y = +1 or y = -1
Or y^2 +1 +1 = 0
y^2 + 2 = 0
y^2 = -2
y = + 2i or y = -2i
So your four possible solutions are
y = { 1, -1, 2i, -2i}
2006-11-21 18:24:48
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answer #2
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answered by mattmedfet 3
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substitute t= y^4 to simplify notation
you get y^4 + y^2 - 2 is t ^2 + t - 2
t^2 + t -2 = (t -1)^2 +3t -3 <-- adding stuff to balance sides
= (t -1)^2 +3(t-1) <-- extract common component (t -1)
= (t -1) (t -1 + 3)
= (t -1) (t +2)
and substitute t back with y^2 to get
y^4 + y^2 - 2 = (y^2)^2 + y^2 - 2 = (y^2 - 1) (y^2 +2)
If you are interested why I considered (t-1)^2 above here is the explanation: t^2+t-2 looks very similar to a solution of
(t +/- 1)^2, therefore I used it as a base. Because it is less than the original expression I had to add something (in this case 3t -3) to balance both sides.
2006-11-22 10:39:06
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answer #3
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answered by homeuser 1
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y^4 + y^2 - 2
The first thing you should notice is that y^4 = y^2 * y^2
Also, the last term is negative. In order to get that, you will need to have a positive multiplied by a negative.
(y^2 + ? )*(y^2 - ? )
Now we need to figure out the last terms. When you multiply them together, they must equal (-2) and when you add them they should equal 1.
2 and (-1) do that, so:
(y^2 + 2 )*(y^2 - 1 )
Also notice that (y^2 - 1 ) is a difference of squares, which can be factored as:
(y - 1)*(y + 1)
So your final answer is:
(y^2 + 2 )*(y - 1)*(y + 1)
2006-11-21 17:59:44
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answer #4
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answered by l337godd3ss 2
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Factors of y^4 + y^2 - 2 are (y^2 + 2) and (y^2 - 1). Do you know how to do it stepwise?
Hope this helps!
2006-11-21 18:01:07
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answer #5
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answered by cfpops 5
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y^4+y^2-2...Factor the first two.
y^2(y^2+1)-2...i think thats all you can do
2006-11-21 17:55:50
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answer #6
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answered by aaylasecura 2
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you're missing an =
2006-11-21 17:55:35
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answer #7
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answered by John T. Woods 2
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