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:

Student #2:

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


Related Post

E-Maths Note: Quadratic Equations & Graphs 3 Different representations of a quadratic equation & its significance y=3x^2 - x + 5 : typical quadratic equation : Max/Min & instant answer...
How to prepare for Maths common test Hi everyone, The Chinese New Year is just over. Certainly hope you have received lots of gifts, plenty of blessings, many ang paos... Well, I am...
A-Math P & C Qn! The no. of applicants for a job is 15. (i)Calculate the no. of ways in which 6 applicants can be selceted for the interview. The six selected appli...
A-Math More Trigo Graphs Another question for O Level Additional Mathematics (A-Math). On the same diagram, sketch the graphs of y=sin 3x & y=cos2x, for x between 0...
How to choose an effective tutor or tuition centre for O Level Students As I was flipping through the papers, there are many advertisements on effective tutors, results,improvements guaranteed, school teachers, scholars et...

Hi, I'm Ai Ling Ong. I enjoy coaching students who have challenges with understanding and scoring in 'O' Level A-Maths and E-Maths. I develop Math strategies, sometimes ridiculous ideas to help students in understanding abstract concepts the fast and memorable way. I write this blog to share with you the stuff I teach in my class, the common mistakes my students made, the 'way' to think, analyze... If you have found this blog post useful, please share it with your friends. I will really appreciate it! :)

One Response to A-Math P & C Clarification

Leave a reply