IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Math => Topic started by: AS-Girl on November 08, 2010, 03:20:27 pm

Title: Challenge for people who loves maths..
Post by: AS-Girl on November 08, 2010, 03:20:27 pm: Hi

I have these questions which i didnt understand, so i was wondering if someone can solve these 4 questions and scan the working out..

The most important thing to me is the working out and explanation...I wrote the answer at the end of each question..Thought it would be helpful

Thanks :)
Title: Re: Challenge for people who loves maths..
Post by: AS-Girl on November 08, 2010, 03:48:26 pm: c'mmon :)
Title: Re: Challenge for people who loves maths..
Post by: elemis on November 08, 2010, 04:14:43 pm: I've done the first one.

Explanation coming up
Title: Re: Challenge for people who loves maths..
Post by: elemis on November 08, 2010, 04:21:59 pm: $3^{1+2x}$ is the same as : ${\color{red} 3^1 *(3^x)^2}$

If $a = \frac{1}{3x}$ then a^-1 = $\frac{1}{\frac{1}{3^x}}$

Hence, $\frac{1}{\frac{1}{3^x}}$ can be simplified as follows :

$1 \div \frac{1}{3^x}$

Thus, 3^x = a^-1

Inputting a^-1 into the red colour equation gives :

3 * (a^-1)²

Giving 3 * a^-2
$<br />3* \frac{1}{a^2}$

Which is basically : $\frac{3}{a^2}$
Title: Re: Challenge for people who loves maths..
Post by: AS-Girl on November 08, 2010, 05:02:29 pm: Got it! thanks Ari Ben Canaan :D :D

need the 3 other questions !!
Title: Re: Challenge for people who loves maths..
Post by: Twinkle Charms on November 08, 2010, 06:55:40 pm: Answer4)

hog(x) is same as hg(x)

g(x)=x/(x+1)

therefore for h(g(x)) u substitute g(x) in place of x in h(x) like this:

h(x)=2x-1 ; in place of x you subs. x/(x+1); ull get : 2x/(x+1) - 1 ; equalise the denominator by multiplyin (x+1) and multiply the numerator with (x+1) also, giving you (2x-x-1)/(x+1) = (x-1)/(x+1) .
Title: Re: Challenge for people who loves maths..
Post by: AS-Girl on November 08, 2010, 08:23:00 pm: Thanks Twinkle Charms!! it really helped :D

2 questions left...
Title: Re: Challenge for people who loves maths..
Post by: Alpha on November 09, 2010, 03:00:08 am: Coming ;)
Title: Re: Challenge for people who loves maths..
Post by: AS-Girl on November 09, 2010, 10:33:43 am: Thanks Alpha..you saved my life :-*

Thanks everyone..once again :)

That's why i love SF hehe
Title: Re: Challenge for people who loves maths..
Post by: Alpha on November 09, 2010, 10:38:22 am: You're most welcome. :)

I love it too. <3