((1^4+1/4)(3^4+1/4)(5^4+1/4).....(19^4+1/4))/((2^4+1/4)(4^4+1/4)(6^4+1/4).....(20^4+1/4)) 10
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a^4+1/4=(a²+1/2)²-a²=(a²+a+1/2)(a²-a+1/2)=[a(a+1)+1/2][a(a-1)+1/2]
所以
[(1^4+1/4)(3^4+1/4)(5^4+1/4)……(19^4+1/4)]/[(2^4+1/4)(4^4+1/4)(6^4+1/4)……(20^4+1/4)]
=[(1*2+1/2)*(1*0+1/2)]·[(3*4+1/2)*(3*2+1/2)]·…·[(19*20+1/2)*(19*18+1/2)]/·[(2*3+1/2)*(2*1+1/2)]·[(4*5+1/2)*(4*3+1/2)]·…·[(20*21+1/2)*(20*19+1/2)]=(1*0+1/2)/(20*21+1/2)=1/841
无意中看到你的提问 就去百度了下 一不小心儿 还给找到了 就复制来了 具体对不对 你自己个儿 验证去吧!!!
所以
[(1^4+1/4)(3^4+1/4)(5^4+1/4)……(19^4+1/4)]/[(2^4+1/4)(4^4+1/4)(6^4+1/4)……(20^4+1/4)]
=[(1*2+1/2)*(1*0+1/2)]·[(3*4+1/2)*(3*2+1/2)]·…·[(19*20+1/2)*(19*18+1/2)]/·[(2*3+1/2)*(2*1+1/2)]·[(4*5+1/2)*(4*3+1/2)]·…·[(20*21+1/2)*(20*19+1/2)]=(1*0+1/2)/(20*21+1/2)=1/841
无意中看到你的提问 就去百度了下 一不小心儿 还给找到了 就复制来了 具体对不对 你自己个儿 验证去吧!!!
参考资料: http://zhidao.baidu.com/question/115665897.html?fr=ala0
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