Q&A - P4 Math

[Jamesbond]

BigDevil:

Figure 3 in the question has 16 blocks, but your formula 3x5-1 = 14 leh :?

So how to derive now....???

[PiggyLalala]

The formula shld be (n+1)^2

[MathIzzzFun]

Jamesbond:

http://i49.tinypic.com/2u6o74j.jpg\">

Pl help me solve this....Thx.

This is a variation of the odd number series...
For odd number series, the sum to the nth odd number is equal to n²


Figure 1
--> 1 + 3 -- 1st odd number + 2nd odd number
--> total number of blocks = 4 = 2² = (1+1)²
--> number of blocks in last row = 2nd odd number = 3 = 2x1+1

Figure 2
--> 1+3+5 -- 1st + 2nd + 3rd odd number
--> Total number of blocks = 9 = 3² = (2+1)²
--> number of blocks in last row = 3rd odd number = 5 = 2x2+1

So..in Figure N
Total number of blocks = (N+1)²
Number of blocks in last row = 2xN +1

a) total number of blocks in figure 6 = (6+1)² = 49
b) figure with 31 blocks in last row = (31-1)/2= 15 --> figure 15
total number of blocks used in figure 15 = 16² = 256

cheers.

[Jamesbond]

Its a new questn for P4…Its from P4… De la salle SA2-2010…


OOPS!!!
Thx mathizzfun…

[Sun_2010]

Jamesbond:

Its a new questn for P4....Its from P4.. De la salle SA2-2010..


OOPS!!!!
Thx mathizzfun...

Good question , thanks for posting it.

If you notice
In fig 1 , if you take unit no 1 and place it over unit no2 , it forms a 2 units square.
In fig 2 if you unit no 4,8,9 and invert it over units 5,2,1 it forms a square on 3 units square.
So on...

Maths is fun!

[Jamesbond]

Sun_2010:

Jamesbond:

Its a new questn for P4....Its from P4.. De la salle SA2-2010..


OOPS!!!!
Thx mathizzfun...

Good question , thanks for posting it.

If you notice
In fig 1 , if you take unit no 1 and place it over unit no2 , it forms a 2 units square.
In fig 2 if you unit no 4,8,9 and invert it over units 5,2,1 it forms a square on 3 units square.
So on...

Maths is fun!

YES.... :boogie:

[heyhoe]

Hi Jamesbond,


Sorry for the confusion. My kid just trying to help.

It’s good that MathIzzFun is able to help. I’ll show this to my DS.

Cheers

[Jamesbond]

heyhoe:

Hi Jamesbond,


Sorry for the confusion. My kid just trying to help.

It's good that MathIzzFun is able to help. I'll show this to my DS.

Cheers

V r here to try and help each other...No worries when v go wrong....I have solved many questions wrongly myself... :imcool:.... Gr8 people in math r always there for r rescue..... :rahrah:

[heyhoe]

Hi,


Appreciate help on the question below:-
The figure below is not drawn to scale. It is made up of a rectangle and 4 identical square. The area shaded part is 275cm square. Find the length of each square.






Thanks.

[heyhoe]

Sorry, I can't seem to get it uploaded although it mentioned \"success\". Any idea how to upload it? :oops:


Cheers,