Question

giúp với mai phải nộp rồi UwU

S=1/1.4+1/4.7+1/7.10+1/10.13+1/13.16

Answer 1

\(S=\dfrac{1}{1.4}+\dfrac{1}{4.7}+\dfrac{1}{7.10}+\dfrac{1}{10.13}+\dfrac{1}{13.16}\)
\(=\dfrac{1}{3}\left(\dfrac{3}{1.4}+\dfrac{3}{4.7}+\dfrac{3}{7.10}+\dfrac{3}{10.13}+\dfrac{3}{13.16}\right)\)
\(=\dfrac{1}{3}\left(1-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{10}+\dfrac{1}{10}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{16}\right)\)
\(=\dfrac{1}{3}\left(1-\dfrac{1}{16}\right)\)
\(=\dfrac{1}{3}\cdot\dfrac{15}{16}\)
\(=\dfrac{5}{16}\)

Answer 2

Chu Tiến Dũng