`1/1 - 1/2 + 1/2 - 1/3 + .. + 1/x - 1/(x+1) = 100/101`
`-> 1/1 - 1/(x+1) = 100/101`
`x/(x+1) = 100/101`
`x = 100`
Đúng 2
Bình luận (1)
Các câu hỏi tương tự
\(B=\left(1+\dfrac{1}{1\cdot3}\right)\left(1+\dfrac{1}{2\cdot4}\right)\left(1+\dfrac{1}{3\cdot5}\right).....\left(1+\dfrac{1}{2021\cdot2023}\right)\)
Tính bằng cách thuận thiện:
\(\left(1+\dfrac{1}{1\cdot3}\right)\left(1+\dfrac{1}{2\cdot4}\right)...\left(1+\dfrac{1}{99\cdot101}\right)\)
Tìm left(xright):
a) left(x-dfrac{1}{2}right)^2:dfrac{2}{9} left(-1dfrac{1}{3}right):left(dfrac{1}{2}-xright)
b) dfrac{3.x-1}{4}dfrac{2.x-5}{3}
c) dfrac{3}{-2}dfrac{x-3}{3.x+1}
Cú tui mấy ông bà ơi:)) Làm dc thì làm giúp tui nhen, cảm ơn nè
Đọc tiếp
Tìm \(\left(x\right)\):
a) \(\left(x-\dfrac{1}{2}\right)^2\):\(\dfrac{2}{9}\) =\(\left(-1\dfrac{1}{3}\right)\):\(\left(\dfrac{1}{2}-x\right)\)
b) \(\dfrac{3.x-1}{4}\)=\(\dfrac{2.x-5}{3}\)
c) \(\dfrac{3}{-2}\)=\(\dfrac{x-3}{3.x+1}\)
Cú tui mấy ông bà ơi:)) Làm dc thì làm giúp tui nhen, cảm ơn nè
9 tháng 1 lúc 20:34
\(\dfrac{3}{4}+\dfrac{1}{4}:x=-2\dfrac{1}{2}\)
\(\left(\dfrac{2}{3}\right)^{100}:x=\left(\dfrac{-2}{3}\right)^{98}\)
\(\dfrac{3}{2}:\left|4x-\dfrac{1}{5}\right|=\dfrac{3}{4}\)
Bài 1
a, A= \(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+...+\dfrac{1}{n\left(n+1\right)}\) ( \(n\in N\) )
b, Chứng minh rằng A<1
Giups mìk vs ạ
Tìm x, biết:
a) \(-\dfrac{2}{3}\left(x+1\right)=\dfrac{1}{6}-x\)
b) \(3\left(x+\dfrac{1}{3}\right)-\dfrac{1}{2}\left(x+2\right)=\dfrac{5}{2}x-1\)
\(3^{2x-1}+2.9^{x-1}=405\)
\(\left(\dfrac{1}{3}\right)^{x-1}+5.\left(\dfrac{1}{3}\right)^{x+1}=\dfrac{14}{9^3}\)
\(\dfrac{3}{5}.\left(3x^3-\dfrac{8}{9}\right)-\dfrac{1}{2}.\left(\dfrac{3}{2}-1\right)=-\dfrac{1}{4}\)
Tìm x ( Giúp với mình cần gấp )
Tìm x,y biết :
a) \(\left|3.x-\dfrac{1}{2}\right|+\left|\dfrac{1}{4}.y+\dfrac{3}{5}\right|\)= 0
b)\(\left|\dfrac{3}{2}.x+\dfrac{1}{9}\right|+\left|\dfrac{5}{7}.y-\dfrac{1}{2}\right|\le0\)
Tìm x biết:
a) \(2.\left|x-1\right|-\dfrac{1}{3}=\dfrac{5}{3}\)
b)\(\dfrac{1}{2}-3:\left|x-\dfrac{1}{2}\right|=\dfrac{1}{3}\)
Tìm x :
1) \(\left(-0,75x+\dfrac{5}{2}\right).\dfrac{4}{7}-\left(-\dfrac{1}{3}\right)=-\dfrac{5}{6}\)
2) \(\left(4x-9\right)\left(2,5+\dfrac{-7}{3}x\right)=0\)
3) \(\left|x-\dfrac{3}{4}\right|-\dfrac{1}{2}=0\)
4)\(\left(\dfrac{3}{5}-\dfrac{2}{3}x\right)^3=\dfrac{-64}{125}\)