## giúp với ạ em cần gấp

Question

giúp với ạ em cần gấp

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11 months 2020-11-10T22:00:12+00:00 1 Answers 47 views 0

## Answers ( )

1. Đáp án:

$$b = – 15;a = – 10;c = – 25$$

Giải thích các bước giải:

$$\begin{array}{l} \left\{ \begin{array}{l} \dfrac{{3a – 2b}}{5} = \dfrac{{2c – 5a}}{3}\\ \dfrac{{3a – 2b}}{5} = \dfrac{{5b – 3c}}{2}\\ a + b + c = – 50 \end{array} \right.\\ \to \left\{ \begin{array}{l} 9a – 6b = 10c – 25a\\ 6a – 4b = 25b – 15c\\ a + b + c = – 50 \end{array} \right.\\ \to \left\{ \begin{array}{l} 34a – 6b – 10c = 0\\ 6a – 29b + 15c = 0\\ a + b + c = – 50 \end{array} \right.\\ \to \left\{ \begin{array}{l} a = – 50 – b – c\\ 6\left( { – 50 – b – c} \right) – 29b + 15c = 0\\ 17a – 3b – 5c = 0 \end{array} \right.\\ \to \left\{ \begin{array}{l} a = – 50 – b – c\\ – 300 – 6b – 6c – 29b + 15c = 0\\ 17a – 3b – 5c = 0 \end{array} \right.\\ \to \left\{ \begin{array}{l} a = – 50 – b – c\\ 9c – 35b – 300 = 0\\ 17a – 3b – 5c = 0 \end{array} \right.\\ \to \left\{ \begin{array}{l} c = \dfrac{{35b + 300}}{9}\\ a = – 50 – b – \dfrac{{35b + 300}}{9}\\ 17a – 3b – 5c = 0 \end{array} \right.\\ \to \left\{ \begin{array}{l} c = \dfrac{{35b + 300}}{9}\\ a = \dfrac{{ – 450 – 9b – 35b – 300}}{9}\\ 17a – 3b – 5c = 0 \end{array} \right.\\ \to \left\{ \begin{array}{l} c = \dfrac{{35b + 300}}{9}\\ a = \dfrac{{ – 750 – 44b}}{9} – \\ 17.\left( {\dfrac{{ – 750 – 44b}}{9}} \right) – 3b – 5.\dfrac{{35b + 300}}{9} = 0\left( * \right) \end{array} \right.\\ \left( * \right) \to \dfrac{{ – 12750 – 748b – 27b – 175b – 1500}}{9} = 0\\ \to – 12750 – 748b – 27b – 175b – 1500 = 0\\ \to – 14250 = 950b\\ \to b = – 15\\ \to a = – 10;c = – 25 \end{array}$$