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Activity-permutations and combinations problems (view source)
Revision as of 14:15, 10 July 2014
, 14:15, 10 July 2014→formulas
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===formulas===
===formulas===
−<math>\{lsup{8}}C_{2}</math>
+<math>{^{8}}C_{2}</math><br>
+<math>{^{n}}C_{r}</math>=<math>\frac{n!}{(n-r)!r!}</math><br>
+<math>{^{8}}C_{2}</math>=<math>\frac{8!}{(8-2)!2!}</math><br>
+=<math>\frac{8!}{6!2!}</math><br>
+=<math>\frac{8x7x6x5x4x3x2x1}{(6x5x4x3x2x1x2x1)}</math><br>
+<math>{^{8}}C_{2}</math>=4x7<br>
+<math>{^{8}}C_{2}</math>=28