Question

Tính hợp lý:

2/3-2/5+2/9+2/13 trên 11/3-11/5+11/9+11/13

Giúp mình nhanh với!!!Bài này khó quá!!!

Answer 1

\(\dfrac{\dfrac{2}{3}-\dfrac{2}{5}+\dfrac{2}{9}+\dfrac{2}{13}}{\dfrac{11}{3}-\dfrac{11}{5}+\dfrac{11}{9}+\dfrac{11}{13}}\)

\(=\dfrac{2\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{9}+\dfrac{1}{13}\right)}{11\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{9}+\dfrac{1}{13}\right)}\)

\(=\dfrac{2}{11}\)

Answer 2

Ta có:

\(\dfrac{\dfrac{2}{3}-\dfrac{2}{5}+\dfrac{2}{9}+\dfrac{2}{13}}{\dfrac{11}{3}-\dfrac{11}{5}+\dfrac{11}{9}+\dfrac{11}{3}}\)

\(=\dfrac{2\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{9}+\dfrac{1}{13}\right)}{11\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{9}+\dfrac{1}{3}\right)}\) Rút gọn \(\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{9}+\dfrac{1}{13}\right)\) ở cả tử và mẫu ta được:

\(=\dfrac{2}{11}\)

Answer 3

\(\dfrac{2.\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{9}+\dfrac{1}{13}\right)}{11.\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{9}+\dfrac{1}{13}\right)}\)

\(=\dfrac{1}{11}\)

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