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hey shkspeare i get what you mean... because there is a formula which looks like this: <sup>n</sup>C<sub>k</sub> = <sup>n-1</sup>C<sub>k-1</sub> + <sup>n-1</sup>C<sub>k</sub> which what ever book you use has used it to derive <sup>6</sup>C<sub>3</sub>. i think you'll learn how to prove this in 2/3u course by the properties of the coefficients of binomial theorem.Originally posted by shkspeare
yes i know how to get 20![]()
i dont get how the books answer simplifies it to <sup>6</sup>C<sub>3</sub> on the next line tho...
construct the pascal triangleOriginally posted by shkspeare
<sup>5</sup>C<sub>2</sub> + <sup>5</sup>C<sub>3</sub> = <sup>6</sup>C<sub>3</sub>
ok i know they both equal to 20
how does the LHS simplify to give RHS![]()
Actually that doesn't help you if you want to do it algebraicly.Originally posted by victorling
construct the pascal triangle
and you will get the clue![]()