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Quadratic equation question help plz

2x^4+14x^2+24
I got one solution but I don't know why the other solution is supposed to be 2(x^2+3) when I divided the equation by 2 at the beginning please help.image.jpg
I can't tell what the question is
Reply 2
Original post by CorpusLuteum
I can't tell what the question is


its at the top
Original post by p29
its at the top


Is the quadratic equal to zero.
Are you only finding x? Why is there a Y.
Be more clear.
Original post by p29
2x^4+14x^2+24
I got one solution but I don't know why the other solution is supposed to be 2(x^2+3) when I divided the equation by 2 at the beginning please help.


As above, be more clear.

Are you solving 2x4+14x2+24=02x^4+14x^2+24=0??? Or are you rearranging for something?

You let y=x2y=x^2 got up to (y+3)(y+4)=0(y+3)(y+4)=0 which is almost correct.

So y=3y=-3 or y=4y=-4

Hence x2=3x^2=-3 or x2=4x^2=-4

Which gives you complex roots.
(edited 7 years ago)
Original post by p29
its at the top


You're overcomplicating it - the solution should only really be three lines max.
Start with the equation, divide by 2, factorise it (as (x2+a)(x2+b)(x^2+a)(x^2+b) of course) and then solve. Just because the quadratic is in x2x^2 as opposed to xx doesn't mean you can't solve it in the normal way.
Reply 6
Original post by RDKGames
As above, be more clear.

Are you solving 2x4+14x2+24=02x^4+14x^2+24=0??? Or are you rearranging for something?

You got up to (y+3)(y+4)=0(y+3)(y+4)=0

So y=3y=-3 or y=4y=-4

Hence x2=3x^2=-3 or x2=4x^2=-4

Which gives you complex roots.

=0 and I have to factorise it
Original post by p29
=0 and I have to factorise it


If you have to factorise it then you've already done it with the y's, so replace them with x2 and you're done.
Reply 8
Original post by p29
=0 and I have to factorise it


the book says that when it is factorised one of them will be 2(x^2+3) which i dont understand
(edited 7 years ago)
Reply 9
????
Reply 10
is the book wrong?
Okay what factorisation have you got so far?
Original post by p29
is the book wrong?


No. You have factored out a 2 at the start so you need to bring it back.

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