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