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Archive for October 2007

Oct/07

6

A-Math Circular Measure

5 marks, showing qn. Another question from GCE O Level Additional Mathematics (A-Math).

:)

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Oct/07

4

A-Math Integration of tan^2 x

Another question from O Level Additional Mathematics (A-Math).

lijun(: said…
i came across this qu that day, and i really want to clarify if the method i used is correct or not.int(tan^2x – x^3)

i changed it to int(sec^2x – 1 – x^3) instead, cos i don’t think we can integrate tan.

is that feasible?

Absolutely. Since tan^2 x can’t be integrated, you must think of alternative by making use of the relationship of tan^2 x + 1 = sec^2 x

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Oct/07

4

A-Math P & C Clarification

Another question from O Level Additional Mathematics (A-Math).

lijun(: said…
hey. i just want to clarify something that i’m not very sure of.

is nCr x r! = nPr ??

By definition,

nCr = nPr/r!

Well, I never remember this ‘rule’
For example, find the number of ways to form a 3 letter word from a,b,c,d,e

Student #1:
5C1*4C1*3C1

Student #2:
5P3

Both answers are correct though different approaches are taken, so no need to remember the ‘rule’

:)

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About Ai Ling

Hi, my name is Ai Ling Ong and I'm a professional Math Trainer specializing in GCE 'O' level Mathematics (Additional & Elementary). More than 10 years of teaching experience, I have coached hundreds of students more than 80 schools in Singapore. Read more about me here
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