Add Maths Oct/Nov 2010 Paper

[leosco1995]

AOA,

I need help with Question 8 of this paper, specifically the last three parts.

Any help would be appreciated.

 

[leosco1995]

Anyone? :s

 

[scouserlfc]

What is the topic which this question belongs

 

[OakMoon!]

Did you look at the marking scheme of this question? I am sure you'll understand after looking at it. It is a simple surd question.
Here is the ms for this paper.

 

[leosco1995]

Yeah, it's a surd question.

Also, I went through the marking scheme but I didn't really get it. Maybe I'm just not good at surds or something, I don't understand how you multiply the root of the equation by sqrt(2) to solve part (ii). After going through it again, I can understand how part (iv) was solved but I still don't get parts (ii) and (iii).

 

[OakMoon!]

sqr(43+30sqr2)=5+3sqr2 Agreed?
86+60sqr(2)=2[43+30sqr(2)] Agreed?
Sqr2*sqr[43+30sqr(2)]=sqr2*(5+3sqr2)

iii) is not even a surds question. It is a simple quadratic expansion. (a+b)^2=a^2+2ab+b^2. Whie (a-b)^2=a^2-2ab+b^2.. So simply write the answer 5-3sqr2. It's a one mark question. 43+30sqr2 is acutally 25+15sqr2+15sqr2+18.. What will you do to change the sign of the sqr2 coeffeicients?

Hope this helped...

 

[leosco1995]

OK, I got part (iii), thanks for the explanation.

I don't get how sqr(43+30(sqr2))=5+3(sqr2). How do you simplify that?

 

[OakMoon!]

Look at the image below for better understanding.

 

[leosco1995]

Oh.., I see. Well, it's a bit tricky (to me at least).

Thanks for the explanation. I got it now.

 

[abcde]

Ummm... wouldn't sqr2 x (5 + 3sqr2) be (5sqr2 + 6) instead of (5sqr2 + 12) ????!

 

[OakMoon!]

Oh! Yes. My mistake. I'll correct it incase there is no confusion. Thankyou abcde for pointing it out.

 

[OakMoon!]

Did you get it completely lesco? If you want I can give further explanation. It was a different question from what usually comes for surds.

 

[abcde]

No problem!

 

[leosco1995]

Yeah, I got it. Thanks for the explanation.

 

[saleena]

Which paper r u talking about paper1 or 2'