Year 12s: what will be the first way you research your future options? >>

c12 help

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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Reply 1

B_9710

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.

Reply 2

thefatone

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}

Reply 3

B_9710

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?

Reply 4

thefatone

Original post by B_9710

Did you read my post above?

my latex is very slow ;(

Reply 5

B_9710

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?

Reply 6

thefatone

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....

Reply 7

B_9710

Original post by thefatone

no....

Can you see where it went wrong?

Reply 8

thefatone

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 ??

Reply 9

B_9710

You put that

\sqrt{x^2} = x

but it doesn't.

\sqrt{x^2} =|x|

Reply 10

Zacken

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.