SOLUTION: Can you please help me evaluate these two expressions? Thank you.
expression 1 = ₉C₂
expression 2 = ₇₀C₃
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-> SOLUTION: Can you please help me evaluate these two expressions? Thank you.
expression 1 = ₉C₂
expression 2 = ₇₀C₃
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You can put this solution on YOUR website! nCr = n!/((n-r)!*r!) ("Combinations" or ways to arrange objects when order doesn't matter)
where:
n! = n*(n-1)*(n-2)*…*3*2*1 (I leave off the *1 when solving problems, it doesn't change anything)
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Expression 1:
Because I've seen these before, if I were writing it out, I'd say to myself 9*8 (because 7, 6, …, 2 will cancel from the (9-2)! = 7! part), divided by 2!=2:
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For expression 2, using the shortcut,
