\(\left(\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+...+\dfrac{1}{9\times10}\right)\times x=\dfrac{3}{4}\)
\(\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{9}-\dfrac{1}{10}\right)\times x=\dfrac{3}{4}\)
\(\left(1-\dfrac{1}{10}\right)\times x=\dfrac{3}{4}\)
\(\dfrac{9}{10}\times x=\dfrac{3}{4}\)
\(x=\dfrac{3}{4}\times\dfrac{10}{9}\)
\(x=\dfrac{5}{6}\)
Tìm x:
(x -\(\dfrac{1}{3}\) ) x (\(\dfrac{2}{1x2}\)+ \(\dfrac{2}{2x3}\)+ \(\dfrac{2}{3x4}\) + … + \(\dfrac{2}{9x10}\)) = \(\dfrac{3}{4}\)
\(\dfrac{1}{1x2}\)+\(\dfrac{1}{2x3}\)+\(\dfrac{1}{3x4}\)+......+\(\dfrac{1}{9x10}\)
Tính bằng cách nhanh nhất
A = \(\dfrac{1}{2}+\dfrac{1}{2x3}+\dfrac{1}{3x4}+............+\dfrac{1}{9x10}\)
tính nhanh
So sánh:
A=\(\dfrac{1}{1x2}\)+\(\dfrac{1}{2x3}\)+.....+\(\dfrac{1}{49x50}\) với 1
B=\(\dfrac{1}{2x4}\)+\(\dfrac{1}{4x6}\)+.....+\(\dfrac{1}{46x48}\) với \(\dfrac{1}{4}\)
C=\(\dfrac{1}{6}\)+\(\dfrac{1}{12}\)+.....+\(\dfrac{1}{110}\)+\(\dfrac{1}{122}\) với \(\dfrac{1}{2}\)
Giải tất cả các câu đầy đủ phép tính giúp mik nha. C.ơn
B= \(\dfrac{1}{1x2}\)+\(\dfrac{1}{2x3}\)+\(\dfrac{1}{3x4}\)+.....+\(\dfrac{1}{198x199}\)+\(\dfrac{1}{199x200}\)
\(\dfrac{1}{2x3}\)+\(\dfrac{1}{1x2}\)+..................+\(\dfrac{1}{^{\text{64x65}}}\)
Tìm x biết:
\(\dfrac{x}{x+1}=\dfrac{1}{1x2}+\dfrac{1}{2x3}+\dfrac{1}{3x4}+...+\dfrac{1}{31x32}\)
Trả lời nhanh giúp mìn nhé
\(\dfrac{\left(\dfrac{1}{6}+\dfrac{1}{10}+\dfrac{1}{15}\right):\left(\dfrac{1}{6}+\dfrac{1}{10}-\dfrac{1}{15}\right)}{\left(\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{4}-\dfrac{1}{5}\right):\left(\dfrac{1}{4}-\dfrac{1}{6}\right)}=\)
Tìm x:
\(\dfrac{1}{3}\) + \(\dfrac{1}{6}\)+ \(\dfrac{1}{10}\)+ ...+ \(\dfrac{1}{xx\left(x+1\right):2}\)= \(\dfrac{2017}{2019}\)
Mọ người giúp em với ạ! Em cảm ơn!
