Vanessa Bingle

Posted on Tuesday, 09 December, 2003 - 09:49 pm:

Please help, this was on my Mock GCSE maths exam and its driving me crazy cos I just don't understand

$x = 2^{k}$

$2^{c} = \sqrt{4 / x}$

What does c=in terms of k Thanks

Emma McCaughan

Posted on Tuesday, 09 December, 2003 - 10:07 pm:

Start by squaring both sides. Do you know what (2^c )² is?

James

Posted on Tuesday, 09 December, 2003 - 10:38 pm:

Alternatively, sub in x. Then use the fact that

\sqrt{a} / \sqrt{b} = \sqrt{a / b}

and simplify top and bottom.

Also remember that $a^{n} \times a^{m} = a^{n + m}$ . You use this to find $\sqrt{2^{k}}$ (sqrt=a power of 1/2)

Hope this helps,

James

Francis Woodhouse

Posted on Wednesday, 10 December, 2003 - 01:09 pm:

Heh, I just did that mock today and had the same question. I did it by solving LaTeX Image

for x, and then equating this to LaTeX Image

. Manipulation of powers will give you the same base on both sides, and hence you can equate the powers.

Don't forget that 4 = 2^2.