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Quadratic formula question

I have the question x^2-3x+4=0 and it says to solve using the quadratic formula. I got 3(plus or minus) (root)-7 all over 2. Sorry its written so poorly haha. Do I leave it in surd form for my answer as I cannot root a negative number or have I made an error? Thanks

I think the answer must be written in surd form
(edited 7 years ago)
Original post by JackLeggett
I have the question x^2-3x+4=0 and it says to solve using the quadratic formula. I got 3(plus or minus) (root)-7 all over 2. Sorry its written so poorly haha. Do I leave it in surd form for my answer as I cannot root a negative number or have I made an error? Thanks


Is this C1 or FP1?

As written, you have not made an error.

Unless it's supposed to be x^2 - 3x - 4 = 0 or something.
Original post by JackLeggett
I have the question x^2-3x+4=0 and it says to solve using the quadratic formula. I got 3(plus or minus) (root)-7 all over 2. Sorry its written so poorly haha. Do I leave it in surd form for my answer as I cannot root a negative number or have I made an error? Thanks


There are no real solutions to that equation.
It can't be solved at this stage.
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JackLeggett
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Original post by SeanFM
Is this C1 or FP1?

As written, you have not made an error.

Unless it's supposed to be x^2 - 3x - 4 = 0 or something.



I am not too sure this was given as homework for my a level taster day and it says to solve it using the quadratic formula
Original post by JackLeggett
I have the question x^2-3x+4=0 and it says to solve using the quadratic formula. I got 3(plus or minus) (root)-7 all over 2. Sorry its written so poorly haha. Do I leave it in surd form for my answer as I cannot root a negative number or have I made an error? Thanks


You should get 3 (plus or minus) root -3 all over 2. Yes you do leave this as a surd because the surd is the exact number, unless the question specifies how many significant figures you leave it to :smile:
Original post by JackLeggett
I have the question x^2-3x+4=0 and it says to solve using the quadratic formula. I got 3(plus or minus) (root)-7 all over 2. Sorry its written so poorly haha. Do I leave it in surd form for my answer as I cannot root a negative number or have I made an error? Thanks


Hmm... Assuming GCSE, that's very unusual, because you do indeed have a negative root, which means that there are no real solutions...

I think they probably just want you to say that there are "no real solutions", unless this is A-level Further Maths and you have met complex numbers...
Original post by JackLeggett
I am not too sure this was given as homework for my a level taster day and it says to solve it using the quadratic formula


If it's FP1 then use −1=i\sqrt{-1}= i,
−7=−17\sqrt{-7} = \sqrt{-1} \sqrt{7}

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