Evaluate { }_{9} C_{2}

Question

Accepted Answer

Step:1 ：The problem is asking for the combination of 9 items taken 2 at a time.Step:2 ：The formula for combination is given by: (C(n, r) = frac{n!}{r!(n-r)!}) where n is the total number of items, r is the number of items to choose, and ! denotes factorial. In this case, n=9 and r=2.Step:3 ：Substituting the values into the formula, we get (C(9, 2) = frac{9!}{2!(9-2)!})Step:4 ：Solving the above expression, we get the combination as 36.Step:5 ：So, the combination of 9 items taken 2 at a time is (boxed{36}).

Answer

Step: 1 ：The problem is asking for the combination of 9 items taken 2 at a time.Step: 2 ：The formula for combination is given by: (C(n, r) = frac{n!}{r!(n-r)!}) where n is the total number of items, r is the number of items to choose, and ! denotes factorial. In this case, n=9 and r=2.Step: 3 ：Substituting the values into the formula, we get (C(9, 2) = frac{9!}{2!(9-2)!})Step: 4 ：Solving the above expression, we get the combination as 36.Step: 5 ：So, the combination of 9 items taken 2 at a time is (boxed{36}).

Evaluate ${ }_{9} C_{2}$

Answer

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