Question

các bạn giúp mình tính bài nay với :

\(A=\frac{\frac{2}{5}+\frac{2}{7}-\frac{2}{9}}{\frac{4}{5}+\frac{4}{7}-\frac{4}{9}}\)

Answer 1

\(A=\frac{\frac{2}{5}+\frac{2}{7}-\frac{2}{9}}{\frac{4}{5}+\frac{4}{7}-\frac{4}{9}}\)

\(=\frac{2.\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{9}\right)}{4.\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{9}\right)}\)

\(=\frac{2}{4}=\frac{1}{2}\)

Answer 2

\(A=\frac{\frac{2}{5}+\frac{2}{7}-\frac{2}{9}}{\frac{4}{5}+\frac{4}{7}-\frac{4}{9}}\)

\(A=\frac{2\left\{\frac{1}{5}+\frac{1}{7}-\frac{1}{9}\right\}}{4\left\{\frac{1}{5}+\frac{1}{7}-\frac{1}{9}\right\}}\)

\(A=\frac{2}{4}=\frac{1}{2}\)