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    i tried and got almost to the answer but got something else at the end.
    i dont understand the last step the answer, if anyone could explain it would be helpful.
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    They have just multiplied  \sqrt 2 x^3 \text{   by   }  \frac{x}{4\sqrt 2}} .

    By the way  \sqrt{x^2} \neq x so even the answer is not correct, unless you have been told that x>0.
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    (Original post by djmans)
    i tried and got almost to the answer but got something else at the end.
    i dont understand the last step the answer, if anyone could explain it would be helpful.
     \sqrt 2 x^3 \times \dfrac{x}{4\sqrt 2} = \dfrac{\sqrt 2 x^4}{4\sqrt 2}
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    (Original post by thefatone)
     \sqrt 2 x^3 \times \dfrac{x}{4\sqrt 2} = \dfrac{\sqrt 2 x^4}{4\sqrt 2}
    Did you read my post above?
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    (Original post by B_9710)
    Did you read my post above?
    my latex is very slow ;(
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    (Original post by thefatone)
    my latex is very slow ;(
    That's not what I'm saying. Try x=-1 in your expression, then do the same thing with the original expression. They should give you the same value, but does it with your expression?
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    (Original post by B_9710)
    That's not what I'm saying. Try x=-1 in your expression, then do the same thing with the original expression. They should give you the same value, but does it with your expression?
    no....
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    (Original post by thefatone)
    no....
    Can you see where it went wrong?
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    (Original post by B_9710)
    Can you see where it went wrong?
    i really don't know....

    but isn't  \sqrt 2 x^3 = \sqrt 2 \times x^3 ??
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    You put that  \sqrt{x^2} = x but it doesn't.
     \sqrt{x^2} =|x| .
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    (Original post by djmans)
    i tried and got almost to the answer but got something else at the end.
    i dont understand the last step the answer, if anyone could explain it would be helpful.
    You may find this thread helpful. I wouldn't worry about the \sqrt{x^2} = |x| thing just yet, it's just a mistake on Edexcel's part.
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    (Original post by Zacken)
    You may find this thread helpful. I wouldn't worry about the \sqrt{x^2} = |x| thing just yet, it's just a mistake on Edexcel's part.
    but shouldn't you rationalise the denominator
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    (Original post by djmans)
    but shouldn't you rationalise the denominator
    You can if you want to, it'll just bean extra step but if that's what if you feel more comfortable with then go ahead.
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    (Original post by Zacken)
    You may find this thread helpful. I wouldn't worry about the \sqrt{x^2} = |x| thing just yet, it's just a mistake on Edexcel's part.
    You need to know sqrt(x^2)=abs(x) for STEP I 2015 Q5(ii), so better to learn it now...
 
 
 
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