式子m(m=1)(m+2)(m+3)(m+4)(m+5)(m+6)...(m+20)/20!可表示为组合问题解的详细点啊
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![式子m(m=1)(m+2)(m+3)(m+4)(m+5)(m+6)...(m+20)/20!可表示为组合问题解的详细点啊](/uploads/image/z/5607457-25-7.jpg?t=%E5%BC%8F%E5%AD%90m%28m%3D1%29%28m%2B2%29%28m%2B3%29%28m%2B4%29%28m%2B5%29%28m%2B6%29...%28m%2B20%29%2F20%21%E5%8F%AF%E8%A1%A8%E7%A4%BA%E4%B8%BA%E7%BB%84%E5%90%88%E9%97%AE%E9%A2%98%E8%A7%A3%E7%9A%84%E8%AF%A6%E7%BB%86%E7%82%B9%E5%95%8A)
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式子m(m=1)(m+2)(m+3)(m+4)(m+5)(m+6)...(m+20)/20!可表示为组合问题解的详细点啊
式子m(m=1)(m+2)(m+3)(m+4)(m+5)(m+6)...(m+20)/20!可表示为
组合问题解的详细点啊
式子m(m=1)(m+2)(m+3)(m+4)(m+5)(m+6)...(m+20)/20!可表示为组合问题解的详细点啊
上下乘以1*2*……*(m-1)=(m-1)!
则原式=(m+20)!/[20!*(m-1)!]
=(m+20)*(m+19)!/[20!*(m-1)!]
=(m+20)*C[(m+19),20]