Tìm x, biết
\(\left(x+\frac{1}{2}\right)+\left(x+\frac{1}{2}\right)+\left(x+\frac{1}{2}\right)=1\)
\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2.\left(x+1\right)}=\frac{99}{100}\)
Tìm x thoả mãn:
a)\(\frac{1}{2}x-\frac{3}{4}x-\frac{7}{3}=-\frac{5}{6}\)
b)\(\frac{4}{5}x-x-\frac{3}{2}x+\frac{4}{3}=\frac{1}{2}-\frac{6}{5}\)
c)\(\frac{1}{1.2}+\frac{1}{2.3}+......+\frac{1}{x.\left(x+1\right)}=\frac{2009}{2010}\)
d)\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x\left(x+1\right)}=1\frac{2013}{2015}\)
e)\(\frac{1}{3.5}+\frac{1}{5.7}+.....+\frac{1}{\left(2x+1\right)\left(2x+3\right)}=\frac{100}{609}\)
1/ Tính tổng:
M =\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}\)
2/Tìm X:
\(\frac{1}{21}+\frac{1}{28} +\frac{1}{36} +.....+\frac{2}{x.\left(x+1\right)}=\frac{2}{9}\)
3/Tính tích sau rồi tìm số nghịch đảo của kết quả:
\(T=\left(1-\frac{1}{3}\right)\left(1-\frac{1}{5}\right)\left(1-\frac{1}{7}\right)\left(1-\frac{1}{9}\right)\left(1-\frac{1}{11}\right)\left(1-\frac{1}{2}\right)\left(1-\frac{1}{4}\right)\left(1-\frac{1}{6}\right)\left(1-\frac{1}{8}\right)\left(1-\frac{1}{10}\right)\)
4/ TÍnh giá trị của biểu thức:
\(\frac{1^2}{1.2}.\frac{2^2}{2.3}.\frac{3^2}{3.4}\frac{4^2}{4.5}\)
a) Tính A=\(\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+..........+\frac{10}{1400}\)
b) Tìm x thuộc Z , biết \(\frac{1.2+2.3+3.4+....+99.100}{x^2+\left(x^2+1\right)+\left(x^2+2\right)+.....+\left(x^2+99\right)}=50\frac{116}{131}\)
Tìm x biết
a \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}...........+\frac{1}{2.\left(x-1\right)}=\frac{999}{1000}\)
b \(\frac{1}{5.8}+\frac{1}{8.11}+\frac{1}{11.14}+.........+\frac{1}{2.\left(x+5\right)}=\frac{101}{1540}\)
\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2019.2020}=\frac{1}{x}\left(x\right)khác0\left(\right)\)
Giair giúp mik nha,cảm ơn các bạn nhìu.
Tính giá trị của các biểu thức sau:
\(C=\left(1+\frac{2}{3}\right).\left(1+\frac{2}{5}\right).\left(1+\frac{2}{7}\right)........\left(1+\frac{2}{2013}\right).\left(1+\frac{2}{2015}\right)\)
\(N=\frac{5.\left(2^2.3^2\right)^9.\left(2^2\right)^6-2.\left(2^2.3\right)^{14}.3^6}{5.2^{28}3^{19}-7.2^{29}.3^{18}}\)
Tìm x biết: \(\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{9.10}\right).\left(x-1\right)=x-\frac{1}{3}\)
tìm x biết \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x.\left(x+1\right)}=\frac{2019}{2020}\)