Comments on: Catching Up With Old Friends http://www.exampaper.com.sg/questions/e-maths/catching-up-with-old-friends Sassy O Level Maths Tuition, Questions & Tips from Singapore's Favourite Private Tutor Sun, 05 Feb 2012 17:08:39 +0000 hourly 1 By: Miss Loi http://www.exampaper.com.sg/questions/e-maths/catching-up-with-old-friends#comment-17068 Miss Loi Tue, 25 Nov 2008 05:12:50 +0000 http://www.exampaper.com.sg/questions/e-maths/catching-up-with-old-friends#comment-17068 <b>Someone:</b> Alright done. You should receive an invoice for Miss Loi's Workings Polishing & Correction Services soon. NETS and credit cards are accepted :P Someone: Alright done.

You should receive an invoice for Miss Loi's Workings Polishing & Correction Services soon. NETS and credit cards are accepted :P

]]> By: Someone http://www.exampaper.com.sg/questions/e-maths/catching-up-with-old-friends#comment-17011 Someone Mon, 24 Nov 2008 09:36:18 +0000 http://www.exampaper.com.sg/questions/e-maths/catching-up-with-old-friends#comment-17011 I made some typos, can help me correct them? the tr2 and extra right bracket ] Haha. I made some typos, can help me correct them? the tr2 and extra right bracket ] Haha.

]]> By: Miss Loi http://www.exampaper.com.sg/questions/e-maths/catching-up-with-old-friends#comment-16963 Miss Loi Sun, 23 Nov 2008 16:19:54 +0000 http://www.exampaper.com.sg/questions/e-maths/catching-up-with-old-friends#comment-16963 Oh heavens, Miss Loi's finally <a href="/miss-loi-the-tutor/where-is-miss-loi" rel="nofollow">done</a>! <b>Someone:</b> Though your solution is mathematically correct, Miss Loi ended up taking much, much longer as <var>x</var>, <var>n</var> and especially <var>t</var><sub>2</sub> (in part 2ii in your workings) turned out to be vastly different in reality! Oh heavens, Miss Loi's finally done!

Someone: Though your solution is mathematically correct, Miss Loi ended up taking much, much longer as x, n and especially t2 (in part 2ii in your workings) turned out to be vastly different in reality!

]]> By: Someone http://www.exampaper.com.sg/questions/e-maths/catching-up-with-old-friends#comment-15810 Someone Tue, 04 Nov 2008 15:38:49 +0000 http://www.exampaper.com.sg/questions/e-maths/catching-up-with-old-friends#comment-15810 1)[tex]t_1=\frac{60}{x}[/tex] 2i)[tex]n=x-2[/tex] 2ii)[tex]t_2=\frac{60}{x-2}[/tex] 3)[tex]t_2-t_1-15=0[/tex] [tex]\frac{60}{x-2}-\frac{60}{x}-15=0[/tex] [tex]\frac{60x}{(x-2)x}-\frac{60(x-2)}{x(x-2)}-15=0[/tex] [tex]\frac{60x-(60x-120)}{x(x-2)}-15=0[/tex] [tex]\frac{60x-60x+120}{x(x-2)}-15=0[/tex] [tex]\frac{120}{x(x-2)}-15=0[/tex] [tex]x(x-2)\times[\frac{120}{x(x-2)}-15]=x(x-2)\times0[/tex] [tex]120-15(x^2-2x)=0[/tex] [tex]120-(15x^2-30x)=0[/tex] [tex]120-15x^2+30x=0[/tex] [tex]-(120-15x^2+30x)=-(0)[/tex] [tex]-120+15x^2-30x=0[/tex] [tex]15x^2-30x-120=0[/tex] [tex]\frac{15x^2-30x-120}{15}=\frac{0}{15}[/tex] [tex]x^2-2x-8=0[/tex] [tex](x+2)(x-4)=0[/tex] [tex]x+2=0[/tex] [tex]x+2-2=0-2[/tex] [tex]x=-2[/tex](rej) [tex]x-4=0[/tex] [tex]x-4+4=0+4[/tex] [tex]x=4[/tex] 4)[tex]n_{total}=10\times4+20\times2=80[/tex] 1)t_1=\frac{60}{x}

2i)n=x-2

2ii)t_2=\frac{60}{x-2}

3)t_2-t_1-15=0

\frac{60}{x-2}-\frac{60}{x}-15=0

\frac{60x}{(x-2)x}-\frac{60(x-2)}{x(x-2)}-15=0

\frac{60x-(60x-120)}{x(x-2)}-15=0

\frac{60x-60x+120}{x(x-2)}-15=0

\frac{120}{x(x-2)}-15=0

x(x-2)\times[\frac{120}{x(x-2)}-15]=x(x-2)\times0

120-15(x^2-2x)=0

120-(15x^2-30x)=0

120-15x^2+30x=0

-(120-15x^2+30x)=-(0)

-120+15x^2-30x=0

15x^2-30x-120=0

\frac{15x^2-30x-120}{15}=\frac{0}{15}

x^2-2x-8=0

(x+2)(x-4)=0

x+2=0

x+2-2=0-2

x=-2(rej)

x-4=0

x-4+4=0+4

x=4

4)n_{total}=10\times4+20\times2=80

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