2a+13b/3a-7b=2c+13d/3c-7d chứng minh a/b=c/d 13/09/2021 Bởi Alexandra 2a+13b/3a-7b=2c+13d/3c-7d chứng minh a/b=c/d
\[\begin{array}{l} gt \to (2a + 13b)(3c – 7d) = (2c + 13d)(3a – 7b)\\ \to 6ac – 14ad + 39bc – 91bd = 6ac – 14bc + 39da – 91bd\\ \to 53bc = 53ad\\ \to bc = ad\\ \to \frac{a}{b} = \frac{c}{d} \end{array}\] Bình luận
\[\begin{array}{l}
gt \to (2a + 13b)(3c – 7d) = (2c + 13d)(3a – 7b)\\
\to 6ac – 14ad + 39bc – 91bd = 6ac – 14bc + 39da – 91bd\\
\to 53bc = 53ad\\
\to bc = ad\\
\to \frac{a}{b} = \frac{c}{d}
\end{array}\]