few sample problems

[mav32]

1.

A B

 

Max surface area covered by 4 Max surface area covered by 1 place mat with

circular place mats with radius R radius 2r.

 

2. [] = absolute value

 

A B

 

[a+b+c] [a]++[c]

 

 

 

3.

 

4-1/x = 4x

 

I thought I did this one right but for some reason my answer is not coming out right.

 

Thanks for the help everyone!!!!!!!

[mav32]

i apologize for question 1. It is supposed to be separated. 4 place mats radius r and 1 place mat radius 2r. Sorry

[hekopeko]

hey , am just beginner in math , but i have an idea about third question

 

what was your answer , 3/4 , or what , here is how this come with me

 

4-1 4x

___ = ___

 

x 1

 

then we can use multiplying method and yield 4x = 4-1 then 3/4

 

maybe am wrong , you have to search more

[Riyad Mohammad]

.2. [] = absolute value

 

A B

 

[a+b+c] [a]++[c]

 

column B is greater. Because [a]++[c] always makes a positive number

[bitsgrasim]

2. Ans D.(can not be determined)

 

Ex.

trail-1 : a =1 b=2 c=3 (A=B)

trail:2 : a=-1 b=-2 c=-3(A=B)

Trail:3 a=1 b=2 c=-3 (A

 

3.

4-(1/x)= 4x

4x-1 =4x^2

=> 4x^2-4x+1=0

=> (2x-1)^2=0

(2x-1)=0

x=1/2

[annabel398]

Question 1:

 

4 mats of radius 1 would cover 4 x (pi x 1squared) = 4pi

 

1 mat of radius 2 would cover 1 x (pi x 2squared) = 4pi

 

Try it with r=3

4 x (pi x 3squared) = 36pi

1 x (pi x 6squared) = 36pi

 

Try it with r=1/2

4 x (pi x 1/2squared) = 1pi

1 x (pi x 1squared) = 1pi

 

The key here is that you're always taking 4 x (the square of the radius) and comparing it to (2 x radius)squared.

Factor (2 x radius)squared = 2squared x radius squared, and since 4 = 2squared, they're going to be the same always.

Edited September 15, 2011 by annabel398