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Mathematics: Post your doubts here!

A

Awesome12

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Umar Ahmed said:
View attachment 36837
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substitute values for d that are prime numbers
for example
lets substitute d=2
the equation will become
x^2 - 6x + 2 = 0
now u cant factorize it (even if it possible then u will get fractions, that are not integers)

the next prime number is 3
x^2 -6x + 3=0
again u cant factorize it

the next prime number is 5
x^2 - 6x +5 = 0
u CAN factorize it
u will get
(x-5)(x-1)
so d=5

another easy way to get a prime no. (which we know has a factor of itself and 1) that when added to 1 will give us 6 (u can derive this rule from factorization)
so 5 +1 = 6
 
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***amd***

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princess sofia said:
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Mathematics (0580)/0580_w05_qp_4.pdf
Q8 part a (ii)
Q7 , part c (ii)
cn any 1 plz explain me thx cnt get it
thnx in advance :p
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Q7 c ii
the volume of 14 cm long part of pipe = pie * 0.125^2 * 0.14 = 0.00687 cubic meters.
that means 0.00687 m^3 of water pass through this in a second.
vol. of pool = 1512 m^3
time taken to to empty the pool = volume/rate = 1512/0.00687 = 220087 seconds.

now we need to convert seconds into hrs. so
22o087 sec = 220087/60 min = 220087/3600 hrs = 61 hrs

and 61 hrs = 2 days and 13 hrs

Q8 a ii
new cost of each book = $(x+2)
no. of book bought in $40 = 40/(x+2)
no of books bought for $(x+2) per book in a total of $40 is '1' less than the no. of books bought for $x per book in a total of $40
that means 40/(x+2) - 1 = (40/x)
simplify it and u'll get the eq .
got it?
 
princess sofia

princess sofia

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***amd*** said:
Q7 c ii
the volume of 14 cm long part of pipe = pie * 0.125^2 * 0.14 = 0.00687 cubic meters.
that means 0.00687 m^3 of water pass through this in a second.
vol. of pool = 1512 m^3
time taken to to empty the pool = volume/rate = 1512/0.00687 = 220087 seconds.

now we need to convert seconds into hrs. so
22o087 sec = 220087/60 min = 220087/3600 hrs = 61 hrs

and 61 hrs = 2 days and 13 hrs

Q8 a ii
new cost of each book = $(x+2)
no. of book bought in $40 = 40/(x+2)
no of books bought for $(x+2) per book in a total of $40 is '1' less than the no. of books bought for $x per book in a total of $40
that means 40/(x+2) - 1 = (40/x)
simplify it and u'll get the eq .
got it?
Click to expand...

yeah thnx :p
 
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