Các câu hỏi tương tự
Tính \(\frac{1}{1.3.5.7}+\frac{1}{3.5.7.9}+\frac{1}{5.7.9.11}+...+\frac{1}{\left(2n+1\right)\left(2n+3\right)\left(2n+5\right)\left(2n+7\right)}\)
Bài 1 : Tìm nin Na) frac{4n-1}{3n+2}in N b) frac{5n-7}{2n+1}in NBài 2 : Tìm nin Na) left(n+2right)cdotleft(2n+5right)21 b) left(2n-3right)cdotleft(n-5right)22Bài 3 : Tìm x.yin Na) left(2n+1right)cdotleft(3y-5right)12 b) left(3x-1right)cdotleft(4y+3right)14Cách bạn giải ra giúp mình nha !
Đọc tiếp
Bài 1 : Tìm \(n\in N\)
a) \(\frac{4n-1}{3n+2}\in N\) b) \(\frac{5n-7}{2n+1}\in N\)
Bài 2 : Tìm \(n\in N\)
a) \(\left(n+2\right)\cdot\left(2n+5\right)=21\) b) \(\left(2n-3\right)\cdot\left(n-5\right)=22\)
Bài 3 : Tìm \(x.y\in N\)
a) \(\left(2n+1\right)\cdot\left(3y-5\right)=12\) b) \(\left(3x-1\right)\cdot\left(4y+3\right)=14\)
Cách bạn giải ra giúp mình nha !
Chứng minh rằng :\(\left(2^{2n+1}\right)^2-\left(2^{n+1}\right)^2=4^{2n+1}+2.2^{2n+1}+1-2^{2n+2}\)
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Chứng minh rằng:
\(\frac{1.3.5.7.9.....\left(2n-1\right)}{\left(n+1\right)\left(n+2\right)\left(n+3\right).....2n}=\frac{1}{2^n}\)
CMR \(\frac{1.3.5.7............\left(2n-1\right)}{\left(n+1\right).\left(n+2\right).\left(n+3\right)............2n}\)=\(\frac{1}{2^n}\)
\(1,\left(n+2\right)⋮\left(n+1\right)\)
2 ,\(8⋮\left(n-2\right)\)
3,\(\left(2n+1\right)⋮\left(6-n\right)\)
4;\(3n⋮\left(n-1\right)\)
5, \(\left(3n+5\right)⋮\left(2n+1\right)\)
6, \(\left(3n+1\right)⋮\left(2n-1\right)\)
CMR : \(\frac{1.3.5.7..............\left(2n-1\right)}{\left(n+1\right)\left(n+2\right)\left(n+3\right)...............2n}\) =\(\frac{1}{^{2^n}}\)
Tìm x:
\(\frac{1}{3}x+\frac{2}{5}\left(x-1\right)=0\)
\(\left(2n-3\right)\left(6-2n\right)=0\)
\(\frac{-2}{3}-\frac{1}{3}\left(2z-5\right)=\frac{3}{2}\)
CMR \(\forall n\in\)N* ta có
\(\left(1-\frac{1}{2}\right)+\left(\frac{1}{3}-\frac{1}{4}\right)+\left(\frac{1}{5}-\frac{1}{6}\right)+...+\left(\frac{1}{2n-1}-\frac{1}{2n}\right)=\frac{1}{n+1}+\frac{1}{n+2}+...+\frac{1}{2n}\)