Math Problem Statement

Which relationships have the same constant of proportionality between y and x as the equation y = 5/2 x?

Solution

The problem is asking which relationships have the same constant of proportionality between yy and xx as the equation y=52xy = \frac{5}{2} x.

To solve this, we will analyze each option and check if the constant of proportionality (the ratio yx\frac{y}{x}) is equal to 52\frac{5}{2}.

  1. Option A: 5y=2x5y = 2x

    • Rearrange to get yy in terms of xx: y=25xy = \frac{2}{5} x
    • The constant of proportionality here is 25\frac{2}{5}, which is not equal to 52\frac{5}{2}.
  2. Option B: 8y=20x8y = 20x

    • Rearrange to get yy in terms of xx: y=208x=52xy = \frac{20}{8} x = \frac{5}{2} x
    • The constant of proportionality is 52\frac{5}{2}, which matches the given equation.
  3. Option C: Graph with a line passing through points (0,0) and (2,5)

    • The slope (constant of proportionality) is given by: slope=ΔyΔx=5020=52\text{slope} = \frac{\Delta y}{\Delta x} = \frac{5 - 0}{2 - 0} = \frac{5}{2}
    • The constant of proportionality is 52\frac{5}{2}, which matches the given equation.
  4. Option D: Graph with a line passing through points (0,0) and (5,2)

    • The slope is: slope=ΔyΔx=2050=25\text{slope} = \frac{\Delta y}{\Delta x} = \frac{2 - 0}{5 - 0} = \frac{2}{5}
    • The constant of proportionality is 25\frac{2}{5}, which is not equal to 52\frac{5}{2}.
  5. Option E: Table of values

    • To check the proportionality, calculate yx\frac{y}{x} for each pair of values:
      • For x=1x = 1, y=2y = 2, we have yx=21=2\frac{y}{x} = \frac{2}{1} = 2.
      • For x=4x = 4, y=10y = 10, we have yx=104=52\frac{y}{x} = \frac{10}{4} = \frac{5}{2}.
      • For x=7x = 7, y=17y = 17, we have yx=177\frac{y}{x} = \frac{17}{7}, which is not 52\frac{5}{2}.
    • Since not all pairs of values match 52\frac{5}{2}, this option does not match.

Final answer:

The relationships that match the given equation are:

  • B
  • C

Would you like more details on how the slopes were calculated?

Here are 5 related questions:

  1. What does a constant of proportionality represent in a linear relationship?
  2. How can you determine the constant of proportionality from a graph?
  3. How would you convert an equation into slope-intercept form to find the constant of proportionality?
  4. How does the constant of proportionality change with different line slopes?
  5. What are the characteristics of direct proportionality in algebraic expressions?

Tip: In equations, always isolate yy to find the constant of proportionality (slope), which makes comparisons easier!

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Math Problem Analysis

Mathematical Concepts

Proportionality
Linear Equations
Graph Analysis
Slope

Formulas

y = kx
slope = Δy/Δx

Theorems

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Suitable Grade Level

Grades 8-10