Which of the following pairs of equations has exactly the same solution?

-3.2x = 0.64 and x/4 = -0.05 x/3.2 = 1.8 and 1.8x = 3.2 3/8x =1 and 1/3x = 1/8 -3/4x = 5/2 and 5/2x = -3/4

1 answer

To determine which pairs of equations have exactly the same solution, we can solve each pair of equations one by one.

  1. First Pair: \( -3.2x = 0.64 \) and \( \frac{x}{4} = -0.05 \)

    Solving \( -3.2x = 0.64 \): \[ x = \frac{0.64}{-3.2} = -0.2 \]

    Solving \( \frac{x}{4} = -0.05 \): \[ x = -0.05 \cdot 4 = -0.2 \]

    Both equations yield the same solution: \( x = -0.2 \).

  2. Second Pair: \( \frac{x}{3.2} = 1.8 \) and \( 1.8x = 3.2 \)

    Solving \( \frac{x}{3.2} = 1.8 \): \[ x = 1.8 \cdot 3.2 = 5.76 \]

    Solving \( 1.8x = 3.2 \): \[ x = \frac{3.2}{1.8} = \frac{32}{18} = \frac{16}{9} \approx 1.78 (not the same as 5.76) \]

    The solutions are not the same.

  3. Third Pair: \( \frac{3}{8}x = 1 \) and \( \frac{1}{3}x = \frac{1}{8} \)

    Solving \( \frac{3}{8}x = 1 \): \[ x = 1 \cdot \frac{8}{3} = \frac{8}{3} \]

    Solving \( \frac{1}{3}x = \frac{1}{8} \): \[ x = \frac{1}{8} \cdot 3 = \frac{3}{8} \]

    The solutions are not the same.

  4. Fourth Pair: \( -\frac{3}{4}x = \frac{5}{2} \) and \( \frac{5}{2}x = -\frac{3}{4} \)

    Solving \( -\frac{3}{4}x = \frac{5}{2} \): \[ x = \frac{5/2}{-3/4} = \frac{5}{2} \cdot \frac{-4}{3} = -\frac{10}{3} \]

    Solving \( \frac{5}{2}x = -\frac{3}{4} \): \[ x = -\frac{3/4}{5/2} = -\frac{3}{4} \cdot \frac{2}{5} = -\frac{3}{10} \]

    The solutions are not the same.

Summary of Results: The first pair of equations, \( -3.2x = 0.64 \) and \( \frac{x}{4} = -0.05 \), has the same solution \( x = -0.2 \). The other pairs do not have the same solution.

Final Answer: The first pair has exactly the same solution.