Maths Question

[Yufster]

Ugh this is so simple I know it but I can't figure it out. I reckon it has something to do with Ratio and Proportions. Help!

 

(iii) The lendth of a rectangle is three times its width. The area of the rectangle is 48cm(squared). Calculate the length of the rectangle.

[Yufster]

Worked it out.....

 

L x B = 48

 

Factors of 48 =

 

6 x 8

12 x 4 <------ These two

24 x 2

 

12 = L, 4 = B

 

OR

 

X x 3X = 48

4x = 48

48

--- = 12

4

 

L = 12.

 

Damn I'm stupid sometimes. Stick around, I may need more help.

[Yufster]

the square root of [ (1.6 / 0.4) - 4 ] is evaluated as -2, right?

[Al-back from the BigWhoop]

actually, theres a lil mistake in the second resolution, X x 3x is 3X^2 (^2=squared), not 4x, so:

 

3X x X = 48

3X^2 = 48

X=16^(1/2) - square root

X=4 which is the width

[Yufster]

I think i meant X + 3X = 4X

[Al-back from the BigWhoop]

well, that wouldnt make any sense, cause L + B ISNT the area but whatever.

 

[ (1.6 / 0.4) - 4 ] ^(1/2)

[4 - 4] ^(1/2)

0^(1/2) = 0

[Yufster]

nother problem....

 

 

 

if Y = X - ZT

.........====

............3

 

then express T in terms of X, Y and Z

 

 

The correct answer is

 

X - 3y

====

...z

 

 

But I can't seem to get that

[Al-back from the BigWhoop]

im assuming this is the problem:

 

Y = X - Zt
  --------
      3


so you do this:

multiply each side by 3
3Y = X - Zt 
add Zt to each side and subtract 3Y from each side
Zt = X - 3Y
divide each side by Z
t = X - 3Y
  --------
      Z

 

accept my suggestion: take more time on the exercises. its better to get them on your own.