tính
1,
\(\frac{0,4-\frac{2}{9}+\frac{2}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}\)
2,
\(\frac{1-\frac{1}{1+\frac{1}{2}}}{1+\frac{1}{1-\frac{1}{2}}}\)
3,
0,8:\(\frac{4}{5}\)-\(\frac{4}{5}\)x(1.08-\(\frac{2}{25}\)) (chú ý x :là dấu nhân)
4,
(1-\(\frac{1}{2}\)) x (1-\(\frac{1}{3}\)) x (1-\(\frac{1}{4}\)) x ......x (1-\(\frac{1}{11}\)) (chú ý x : là dấu nhân ; dấu .... là vân vân )