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Answer 1

$a, 13 x + 7 = - 17 x - 23 \Leftrightarrow 13 x + 17 x = - 23 - 7 \Leftrightarrow 30 x = - 30 \Leftrightarrow x = - 1 V â y x = - 1 b, \frac{x}{3} - \frac{2 x + 1}{2} = \frac{x}{6} - x \Leftrightarrow \frac{2 x - 3 . (2 x + 1)}{6} = \frac{x - 6 x}{6} \Leftrightarrow \frac{- 4 x - 3}{6} = \frac{- 5 x}{6} \Leftrightarrow - 4 x - 3 = - 5 x \Leftrightarrow x = 3 V ậ y x = 3 c, 5 - (x - 6) = 4 (3 - 2 x) + 13 \Leftrightarrow 5 - x + 6 - 12 + 8 x - 13 = 0 \Leftrightarrow 7 x - 14 = 0 \Leftrightarrow 7 x = 14 \Leftrightarrow x = 2 V ậ y x = 2 d) (2 x - 5) (4 x + 7) (3 x - 15) = 0 \Leftrightarrow 2 x - 5 = 0 h o ặ c 4 x + 7 = 0 h o ặ c 3 x - 15 = 0 \Leftrightarrow \begin{array}{rcl} x & = & \frac{5}{2} \\ x & = & \frac{- 7}{4} \\ x & = & \frac{15}{3} = 5 \end{array} v ậ y x = \frac{5}{2}; \begin{array}{rcl} x & = & \frac{- 7}{4} \end{array}; x = 5 e) - 15 | x | = - 15 \Leftrightarrow |x| = 1 \Leftrightarrow x = \pm 1 v ậ y x = \pm 1 f, x^{2} - 2 x - 8 = 0 \Leftrightarrow x^{2} - 4 x + 2 x - 8 = 0 \Leftrightarrow (x - 4) . (x + 2) = 0 \Leftrightarrow \begin{array}{rcl} x - 4 & = & 0 \\ x + 2 & = & 0 \end{array} \Leftrightarrow x = 4 h o ặ c x = - 2$

Vậy x=4 hoặc x=-2

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Answer 2

$a, 13 x + 7 = - 17 x - 23 \Leftrightarrow 13 x + 17 x = - 23 - 7 \Leftrightarrow 30 x = - 30 \Leftrightarrow x = - 1 V â y x = - 1 b, \frac{x}{3} - \frac{2 x + 1}{2} = \frac{x}{6} - x \Leftrightarrow \frac{2 x - 3 . (2 x + 1)}{6} = \frac{x - 6 x}{6} \Leftrightarrow \frac{- 4 x - 3}{6} = \frac{- 5 x}{6} \Leftrightarrow - 4 x - 3 = - 5 x \Leftrightarrow x = 3 V ậ y x = 3 c, 5 - (x - 6) = 4 (3 - 2 x) + 13 \Leftrightarrow 5 - x + 6 - 12 + 8 x - 13 = 0 \Leftrightarrow 7 x - 14 = 0 \Leftrightarrow 7 x = 14 \Leftrightarrow x = 2 V ậ y x = 2 d) (2 x - 5) (4 x + 7) (3 x - 15) = 0 \Leftrightarrow 2 x - 5 = 0 h o ặ c 4 x + 7 = 0 h o ặ c 3 x - 15 = 0 \Leftrightarrow \begin{array}{rcl} x & = & \frac{5}{2} \\ x & = & \frac{- 7}{4} \\ x & = & \frac{15}{3} = 5 \end{array} v ậ y x = \frac{5}{2}; \begin{array}{rcl} x & = & \frac{- 7}{4} \end{array}; x = 5 e) - 15 | x | = - 15 \Leftrightarrow |x| = 1 \Leftrightarrow x = \pm 1 v ậ y x = \pm 1 f, x^{2} - 2 x - 8 = 0 \Leftrightarrow x^{2} - 4 x + 2 x - 8 = 0 \Leftrightarrow (x - 4) . (x + 2) = 0 \Leftrightarrow \begin{array}{rcl} x - 4 & = & 0 \\ x + 2 & = & 0 \end{array} \Leftrightarrow x = 4 h o ặ c x = - 2$

Vậy x=4 hoặc x=-2

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