Question

Giúp mk với đg cần gấp lắm

7/3+7/15+7/35+7/63+7/99+7/143+7/195

Answer 1

=7/2.(2/1.3+2/3.5+....+2/13.15)

=7/2.(1/1-1/3+1/3-1/5+....+1/13-1/15)

=7/2.(1-1/15)

=7/2.14/15=7.14/2.25

=7.7/1/15=49/15

Answer 2

Ai làm nhanh mk cho nah

Answer 3

\(\frac{7}{1\cdot3}+\frac{7}{3\cdot5}+\frac{7}{5\cdot7}+\frac{7}{7\cdot9}+\frac{7}{9\cdot11}+\frac{7}{11\cdot13}+\frac{7}{13\cdot15}\)

\(=\frac{7}{2}\left(\frac{2}{1\cdot3}+\frac{2}{3\cdot5}+..........+\frac{2}{13\cdot15}\right)\)

\(=\frac{7}{2}\left(\frac{2}{1}-\frac{2}{3}+\frac{2}{3}-\frac{2}{5}+.........+\frac{2}{13}-\frac{2}{15}\right)\)

\(=\frac{7}{2}\left(2-\frac{2}{15}\right)=\frac{98}{15}\)

Answer 4

1189/364