Học tại trường Chưa có thông tin
Đến từ Hà Nội , Chưa có thông tin
Số lượng câu hỏi 36
Số lượng câu trả lời 4685
Điểm GP 117
Điểm SP 176

Người theo dõi (10)

Đang theo dõi (8)

Cô Tuyết Ngọc
Đỗ Tuệ Lâm
Hà Đức Thọ
Hữu Nghĩa

Câu trả lời:

\(a.\) \(A=\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+\dfrac{1}{4\cdot5}+\dfrac{1}{5\cdot6}+\dfrac{1}{6\cdot7}\)

\(A=\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}\)

\(A=\dfrac{1}{2}-\dfrac{1}{7}\)

\(A=\dfrac{7}{14}-\dfrac{2}{14}\)

\(A=\dfrac{5}{14}\)

\(b.\) \(D=\dfrac{2}{3\cdot4}+\dfrac{2}{4\cdot5}+...+\dfrac{2}{2022\cdot2023}\)

\(D=\dfrac{2}{3}-\dfrac{2}{4}+\dfrac{2}{4}-\dfrac{2}{5}+...+\dfrac{2}{2022}-\dfrac{2}{2023}\)

\(D=\dfrac{2}{3}-\dfrac{2}{2023}\)

\(D=\dfrac{4046}{6069}-\dfrac{6}{6069}\)

\(D=\dfrac{4040}{6969}\)

\(c.\) \(E=\dfrac{1}{1\cdot4}+\dfrac{1}{4\cdot7}+...+\dfrac{1}{37\cdot40}\)

\(E=\dfrac{1}{1}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+...+\dfrac{1}{37}-\dfrac{1}{40}\)

\(E=\dfrac{1}{4}-\dfrac{1}{40}\)

\(E=\dfrac{10}{40}-\dfrac{1}{40}\)

\(E=\dfrac{9}{40}\)

\(d.\) \(J=\dfrac{1\cdot2\cdot3+2\cdot4\cdot6+4\cdot8\cdot12+7\cdot14\cdot21}{1\cdot3\cdot5+2\cdot6\cdot10+4\cdot12\cdot20+7\cdot21\cdot35}+\dfrac{3}{5}\)

\(J=\dfrac{1\cdot2\cdot3+1\cdot2\cdot3\cdot2\cdot2\cdot2+1\cdot2\cdot3\cdot4\cdot4\cdot4+1\cdot2\cdot3\cdot7\cdot7\cdot7}{1\cdot3\cdot5+1\cdot2\cdot5\cdot2\cdot2\cdot2+1\cdot2\cdot5\cdot4\cdot4\cdot4+1\cdot2\cdot3\cdot7\cdot7\cdot7}+\dfrac{3}{5}\)

\(J=\dfrac{1\cdot2\cdot3\cdot\left(1+2^3+4^3+7^3\right)}{1\cdot3\cdot5\cdot\left(1+2^3+4^3+7^3\right)}+\dfrac{3}{5}\)

\(J=\dfrac{1\cdot2\cdot3}{1\cdot3\cdot5}\cdot1+\dfrac{3}{5}\)

\(J=\dfrac{6}{15}+\dfrac{3}{5}\)

\(J=\dfrac{2}{5}+\dfrac{3}{5}\)

\(J=\dfrac{5}{5}=1\)