\(\frac{\left(-\frac{1}{7}\right)^n}{\left(-\frac{1}{7}\right)^{n+2}}\)
LT
Những câu hỏi liên quan
frac{1}{3}-frac{3}{5}+frac{5}{7}-frac{7}{9}+frac{9}{11}-frac{11}{13}+frac{11}{15}+frac{11}{13}-frac{9}{11}+frac{7}{9}-frac{5}{7}+frac{3}{5}-frac{1}{3}frac{-3}{4}.31frac{11}{23}-0,75.8frac{12}{28}left(2frac{1}{3}+3frac{1}{2}right):left(-4frac{1}{6}+3frac{1}{7}right)+7frac{1}{2}4frac{5}{9}:left(-frac{5}{7}right)+5frac{4}{9}:left(-frac{5}{7}right)frac{2}{3}-4left(frac{1}{2}+frac{3}{4}right)left(1-frac{1}{2}right).left(1-frac{1}{3}right).left(1-frac{1}{4}right)....left(1-frac{1}{n+1}right)nin Z
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\(\frac{1}{3}-\frac{3}{5}+\frac{5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}+\frac{11}{15}+\frac{11}{13}-\frac{9}{11}+\frac{7}{9}-\frac{5}{7}+\frac{3}{5}-\frac{1}{3}\)\(\frac{-3}{4}.31\frac{11}{23}-0,75.8\frac{12}{28}\)\(\left(2\frac{1}{3}+3\frac{1}{2}\right):\left(-4\frac{1}{6}+3\frac{1}{7}\right)+7\frac{1}{2}\)\(4\frac{5}{9}:\left(-\frac{5}{7}\right)+5\frac{4}{9}:\left(-\frac{5}{7}\right)\)\(\frac{2}{3}-4\left(\frac{1}{2}+\frac{3}{4}\right)\)\(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)....\left(1-\frac{1}{n+1}\right)n\in Z\)
Tính :a, frac{frac{left(-5right)^n}{left(7right)}}{frac{left(-5right)^{n-1}}{7}}left(n1right) b,frac{frac{left(-1right)^{2n}}{2}}{frac{left(-1right)^n}{2}}left(nin Nright)Phân số frac{-5}{7}và frac{-1}{2}nằm trong ngoặc nhưng mình chỉ đóng ngoặc đc tử nên đừng hiểu sai nhaAi nhanh mình tick
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Tính :
a, \(\frac{\frac{\left(-5\right)^n}{\left(7\right)}}{\frac{\left(-5\right)^{n-1}}{7}}\left(n>=1\right)\) b,\(\frac{\frac{\left(-1\right)^{2n}}{2}}{\frac{\left(-1\right)^n}{2}}\left(n\in N\right)\)
Phân số \(\frac{-5}{7}\)và \(\frac{-1}{2}\)nằm trong ngoặc nhưng mình chỉ đóng ngoặc đc tử nên đừng hiểu sai nha
Ai nhanh mình tick
Rút gọn \(A=\frac{3}{\left(1.2\right)^2}+\frac{5}{\left(2.3\right)^2}+\frac{7}{\left(3.4\right)^2}+...+\frac{2n+1}{\left[n\left(n+1\right)\right]^2}\)
Ta có:
\(A=\frac{3}{\left(1.2\right)^2}+\frac{5}{\left(2.3\right)^2}+\frac{7}{\left(3.4\right)^2}+...+\frac{2n+1}{\left[n\left(n+1\right)\right]^2}\)
\(=\frac{3}{1^2.2^2}+\frac{5}{2^2.3^2}+\frac{7}{3^2.4^2}+...+\frac{2n+1}{n^2\left(n+1\right)^2}\)
\(=\frac{3}{1.4}+\frac{5}{4.9}+\frac{7}{9.16}+...+\frac{2n+1}{n^2\left(n+1\right)^2}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{9}+...+\frac{2n+1}{n^2}-\frac{2n+1}{\left(n+1\right)^2}\)
\(=1-\frac{2n+1}{\left(n+1\right)^2}\)
Vậy \(A=\frac{2n+1}{\left(n+1\right)^2}\)
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a,frac{-1}{24}-left[frac{1}{4}-left(frac{1}{2}-frac{7}{8}right)right]
b,left[frac{5}{7}-frac{7}{5}right]-left[frac{1}{2}-left(frac{-2}{7}-frac{1}{10}right)right]
c,left(frac{-1}{2}right)-left(frac{-3}{5}right)+left(frac{-1}{9}right)+frac{1}{71}-left(frac{-2}{7}right)+frac{4}{35}-frac{7}{8}
d,left(3-frac{1}{4}+frac{2}{3}right)-left(5-frac{1}{3}-frac{6}{5}right)-left(6-frac{7}{4}+frac{3}{2}right)
e,left(frac{1}{2}-frac{13}{14}right):frac{5}{7}-left(frac{-2}{21}+frac{1}{7}right):frac{5}{7}
g,f...
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a,\(\frac{-1}{24}-\left[\frac{1}{4}-\left(\frac{1}{2}-\frac{7}{8}\right)\right]\)
b,\(\left[\frac{5}{7}-\frac{7}{5}\right]-\left[\frac{1}{2}-\left(\frac{-2}{7}-\frac{1}{10}\right)\right]\)
c,\(\left(\frac{-1}{2}\right)-\left(\frac{-3}{5}\right)+\left(\frac{-1}{9}\right)+\frac{1}{71}-\left(\frac{-2}{7}\right)+\frac{4}{35}-\frac{7}{8}\)
d,\(\left(3-\frac{1}{4}+\frac{2}{3}\right)-\left(5-\frac{1}{3}-\frac{6}{5}\right)-\left(6-\frac{7}{4}+\frac{3}{2}\right)\)
e,\(\left(\frac{1}{2}-\frac{13}{14}\right):\frac{5}{7}-\left(\frac{-2}{21}+\frac{1}{7}\right):\frac{5}{7}\)
g,\(\frac{4}{9}:\left(\frac{-1}{7}\right)+6\frac{5}{9}:\left(\frac{-1}{7}\right)\)
Chứng minh: \(\frac{1}{3\left(1+\sqrt{2}\right)}+\frac{1}{5\left(\sqrt{2}+\sqrt{3}\right)}+\frac{1}{7\left(\sqrt{3}+\sqrt{4}\right)}+...+\frac{1}{\left(2n+1\right)\left(\sqrt{n}+\sqrt{n+1}\right)}\)\(< \frac{1}{2}\)
Bài 1 :a, Tính tổng\(S=\left(-\frac{1}{7}\right)^0+\left(-\frac{1}{7}\right)^1+\left(-\frac{1}{7}\right)^2+.......+\left(-\frac{1}{7}\right)^{2007}\)
b, CMR \(\frac{1}{2!}+\frac{2}{3!}+\frac{3}{4!}+.......+\frac{99}{100!}<1\)
c, CMR: mọi số nguyên dương n thì: \(3^{n+2}-2^{n+2}+3^n-2^n\)chia hết cho 10
3n+2 - 2n+2 +3n - 2n = 3n . 32 - 2n. 22 +3n -2n
= 3n(32+1) - (2n.22 +2n)
=3n . 10 - 2n .5
=3n.10 - 2n-1 .2 .5
= 3n.10 - 2n-1 .10
= 10(3n - 2n-1)
vì 10 chia hết cho 10 nên 10(3n-2n-1) chia hết cho 10
=> 3n+2 - 2n+2 +3n -2n chia hết cho 10
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Ai làm nhanh nhất mình sẽ **** xin cảm ơn các bạn mình đang cần gấp
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Tính :
a) \(\frac{\left(\frac{-5}{7}\right)^n}{\left(\frac{-5}{7}\right)^{n-1}}\)( n\(\ge\)1 )
b) \(\frac{\frac{-1}{2}^{2n}}{\left(\frac{-1}{2}\right)^n}\) ( n \(\in\)N )
a: \(=\dfrac{\left(-\dfrac{5}{7}\right)^n}{\left(-\dfrac{5}{7}\right)^n\cdot\dfrac{-7}{5}}=1:\dfrac{-7}{5}=-\dfrac{5}{7}\)
b: \(=\dfrac{\dfrac{1}{4}^n}{\left(-\dfrac{1}{2}\right)^n}=\left(-\dfrac{1}{2}\right)^n\)
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\(D=\frac{\left(2!\right)^2}{1^2}+\frac{\left(2!\right)^2}{3^2}+\frac{\left(2!\right)^2}{5^2}+\frac{\left(2!\right)^2}{7^2}+...+\frac{\left(2!\right)^2}{2015^2}\)
So sánh D với 6. Biết n! = 1.2.3....n ( n thuộc N )
Bài 1 Thưc hiện phép tính ( tính nhanh nếu có thể)a)frac{-1}{24}-left[frac{1}{4}-left(frac{1}{2}-frac{7}{8}right)right]b)left(frac{5}{7}-frac{7}{5}right)-left[frac{1}{2}-left(frac{-2}{7}-frac{1}{10}right)right]C)left(frac{-1}{2}right)-left(frac{-3}{5}right)+left(frac{-1}{9}right)+frac{1}{17}-left(frac{-2}{7}right)+frac{4}{35}-frac{7}{18}d)left(3-frac{1}{4}+frac{2}{3}right)-left(5-frac{1}{3}-frac{6}{5}right)-left(6-frac{7}{4}+frac{3}{2}right)
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Bài 1 Thưc hiện phép tính ( tính nhanh nếu có thể)
a)\(\frac{-1}{24}-\left[\frac{1}{4}-\left(\frac{1}{2}-\frac{7}{8}\right)\right]\)
b)\(\left(\frac{5}{7}-\frac{7}{5}\right)-\left[\frac{1}{2}-\left(\frac{-2}{7}-\frac{1}{10}\right)\right]\)
C)\(\left(\frac{-1}{2}\right)-\left(\frac{-3}{5}\right)+\left(\frac{-1}{9}\right)+\frac{1}{17}-\left(\frac{-2}{7}\right)+\frac{4}{35}-\frac{7}{18}\)
d)\(\left(3-\frac{1}{4}+\frac{2}{3}\right)-\left(5-\frac{1}{3}-\frac{6}{5}\right)-\left(6-\frac{7}{4}+\frac{3}{2}\right)\)