The price for footballs. Derive the equation of the proportional relationship through the origin

first point (1,9) second point (2, 18) third point (3, 27) fourth point (4, 36)

1 answer

To derive the equation of the proportional relationship through the origin from the given points, we need to identify the constant of proportionality.

The points you provided are:

  • (1, 9)
  • (2, 18)
  • (3, 27)
  • (4, 36)

In a proportional relationship, if \( y \) is directly proportional to \( x \), then the relationship can be expressed as:

\[ y = kx \]

where \( k \) is the constant of proportionality.

We can find \( k \) using any of the points provided. Let's use the first point (1, 9):

Given \( x = 1 \) and \( y = 9 \):

\[ 9 = k(1) \] \[ k = 9 \]

Now, we can write the equation of the proportional relationship:

\[ y = 9x \]

To confirm this relationship holds for the other points:

  • For (2, 18): \[ y = 9(2) = 18 \quad \text{(correct)} \]

  • For (3, 27): \[ y = 9(3) = 27 \quad \text{(correct)} \]

  • For (4, 36): \[ y = 9(4) = 36 \quad \text{(correct)} \]

Thus, the derived equation of the proportional relationship through the origin is:

\[ y = 9x \]