Question

( \(\frac{2}{11\cdot13}\)+ \(\frac{2}{13\cdot15}\)+.......+\(\frac{2}{19\cdot21}\)) x 623 - 24,808 :(y+0,5) +12,04=30

Answer 1

\(\left(\frac{2}{11.13}+\frac{2}{13.15}+.........+\frac{2}{19.21}\right)x623-24,808:\left(y+0,5\right)+12,04=30\)

Ta tính bên trong ngoặc:

\(\frac{2}{11.13}+\frac{2}{13.15}+..........+\frac{2}{19.21}\)

= \(\frac{2}{11}-\frac{2}{13}+\frac{2}{13}-\frac{2}{15}+...........+\frac{2}{19}-\frac{2}{21}\)

= \(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+.........+\frac{1}{19}-\frac{1}{21}\)

=> \(\frac{1}{11}-\frac{1}{19}\)= \(\frac{8}{209}\)

=> \(\frac{8}{209}x623-24,808:\left(y+0,5\right)+12,04=30\)

      Tiếp tục làm tiếp nhé

Answer 2

Nhầm mk làm lại:

\(\frac{1}{11}-\frac{1}{21}=\frac{10}{231}\)

=> \(\frac{10}{231}x623-24,808:\left(y+05\right)+12,04=30\)

      \(\frac{890}{33}\)- 24,808 : .......

Làm tiếp đi nhé