(1/2.5+1/5.8+......+1/65.68)x=19/68+7/34=33/68
(1/2.5+1/5.8+.......+1/65.68).x.3=33/68.3=99/68
(3/2.5+3/5.8=.......+3/65.68).x=99/68
(1/2-1/5+1/5-1/8+....-+1/65-1/68).x=99/68
(1/2-1/68).x=99/68
33/68.x=99/68
=>x=3
k cho mình nha
Tìm x biết: \(\left(\frac{1}{2\cdot5}+\frac{1}{5\cdot8}+\frac{1}{8\cdot11}+...+\frac{1}{65\cdot68}\right)x-\frac{7}{34}=\frac{19}{68}\)
Tìm x biết :\(\left(\frac{1}{2\cdot5}+\frac{1}{5\cdot8}+\frac{1}{8\cdot11}+...+\frac{1}{65\cdot68}\right)x-\frac{7}{34}=\frac{19}{68}\)
Tìm số nguyên âm a biết:
\(a^2-\left(\frac{3}{5}\right)^2=\frac{1}{1\cdot2}+\frac{1}{2\cdot7}+\frac{1}{7\cdot5}+\frac{1}{5\cdot13}+\frac{1}{13\cdot8}+\frac{1}{8\cdot19}+\frac{1}{19\cdot11}+\frac{1}{11\cdot25}\)
Tìm số nguyên âm a biết:
\(a^2-\left(\frac{3}{5}\right)^2=\frac{1}{1\cdot2}+\frac{1}{2\cdot7}+\frac{1}{7\cdot5}+\frac{1}{5\cdot13}+\frac{1}{13\cdot8}+\frac{1}{8\cdot19}+\frac{1}{19\cdot11}+\frac{1}{11\cdot25}\)
\(S=\frac{1}{2\cdot5}+\frac{1}{5\cdot8}+\frac{1}{8\cdot11}+...+\frac{1}{\left(3n-1\right)\left(3n+2\right)}\) giúp em tìm công thức với ạ
Tìm số nguyên dương a thoả mãn:
\(a^2-\left(\frac{3}{5}\right)^2=\frac{1}{1\cdot2}+\frac{1}{2\cdot7}+\frac{1}{7\cdot5}+\frac{1}{5\cdot13}+\frac{1}{13\cdot8}+\frac{1}{8\cdot19}+\frac{1}{19\cdot11}+\frac{1}{11\cdot25}\)
Ai làm nhanh nhất thì mình tick cho
\(A=\frac{8\frac{3}{9}\cdot5\frac{1}{4}+3\frac{16}{19}\cdot5\frac{1}{4}}{\left(2\frac{14}{17}-2\frac{1}{34}\right)\cdot34}:\frac{7}{24}\)
Tính tổng 1000 số hạng trong dãy số sau
\(1\frac{1}{3};1\frac{1}{8};1\frac{1}{15};...\)
Tìm x :
\(\frac{1}{5\cdot8}+\frac{1}{8\cdot11}+\frac{1}{11\cdot14}+...+\frac{1}{x\left(x+3\right)}=\frac{101}{1540}\)
Tìm x biết:\(\left(\frac{1}{2.5}+\frac{1}{5.8}+\frac{1}{8.11}+...+\frac{1}{65.68}\right)x-\frac{7}{34}=\frac{19}{68}\)Trả Lời x =