mình thích làm tắt

\(ĐKXĐ:x\ne\pm2\)

\(\dfrac{x+1}{x-2}+\dfrac{x-1}{x+2}=\dfrac{2\left(x^2+2\right)}{x^2-4}\)

\(\Leftrightarrow\dfrac{x+1}{x-2}+\dfrac{x-1}{x+2}=\dfrac{2\left(x^2+2\right)}{\left(x-2\right)\left(x+2\right)}\)

\(\Leftrightarrow\dfrac{\left(x+1\right)\left(x+2\right)+\left(x-1\right)\left(x-2\right)}{\left(x-2\right)\left(x+2\right)}\)

\(\Leftrightarrow\dfrac{2\left(x^2+2\right)}{\left(x-2\right)\left(x+2\right)}\)

\(\Rightarrow\left(x+1\right)\left(x+2\right)+\left(x-1\right)\left(x-2\right)=2\left(x^2+2\right)\)

\(\Leftrightarrow x^2+x+2x+2+x^2-x-2x+2=2x^2+4\)

Ta có:

\(G=\dfrac{1}{2^2}+\dfrac{1}{4^2}+\dfrac{1}{6^2}+.....+\dfrac{1}{100^2}\)

\(G=\dfrac{1}{4}\left(1+\dfrac{1}{2^2}+\dfrac{1}{3^2}+......+\dfrac{1}{50^2}\right)\)

\(G< \dfrac{1}{4}\left(1+\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+....+\dfrac{1}{99.100}\right)\)

\(G=\dfrac{1}{4}\left(1+1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+..........+\dfrac{1}{99}-\dfrac{1}{100}\right)\)

\(G=\dfrac{1}{4}\left(2-\dfrac{1}{100}\right)\)

\(\Rightarrow G< \dfrac{1}{2}\left(đpcm\right)\)

How manny groups of languages  all ethinic groups speak

\(\dfrac{1}{100};\dfrac{100}{1};\dfrac{20}{5};\dfrac{5}{20};\dfrac{25}{4};\dfrac{4}{25}\)

B nha

Câu hỏi ngoằn ngoèo , lặp lại

đâu thấy gì đâu

Đáp án đâu

Chắc rơi ở đâu chứ còn , làm j có chuyện rơi ở đây :)

Danh từ

Xem phim lãng mạn Hollywood đầy r