Question

[Third Lapat Ngamchaweng]

1. Tính hợp lí :

\(\frac{1}{1.3}\)+ \(\frac{1}{3.5}\)+ \(\frac{1}{5.7}\)+ \(\frac{1}{7.9}\)+ \(\frac{1}{9.11}\)+ \(\frac{1}{11.13}\)

2.Tìm x biết :

1+\(\frac{-1}{60}\)+ \(\frac{19}{120}\)< \(\frac{x}{36}\)< \(\frac{58}{90}\)+ \(\frac{59}{72}\)+ \(\frac{-1}{60}\)

Answer 1

[Đợi anh khô nước mắt]

1/ \(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+\frac{1}{9.11}+\frac{1}{11.13}\)

\(=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+\frac{1}{11}-\frac{1}{13}\)

\(=1-\frac{1}{13}=\frac{12}{13}\)

Answer 2

[Cao Thi Huyen trang]

bằng 12 /13 nha bn