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What is the constant of proportionality in the equation StartFraction x over y EndFraction StartFraction 2 over 9 EndFraction?
StartFraction 2 over 9 EndFraction
2
StartFraction 9 over 2 EndFraction
9


Sagot :

Given:

The equation is:

[tex]\dfrac{x}{y}=\dfrac{2}{9}[/tex]

To find:

The constant of proportionality.

Solution:

If y is directly proportional to x, then

[tex]y\propto x[/tex]

[tex]y=kx[/tex]                        ...(i)

Where, k is the constant of proportionality.

We have,

[tex]\dfrac{x}{y}=\dfrac{2}{9}[/tex]

On cross multiplication, we get

[tex]9x=2y[/tex]

Divide both sides by 2.

[tex]\dfrac{9}{2}x=y[/tex]

Interchange the sides.

[tex]y=\dfrac{9}{2}x[/tex]                ...(ii)

On comparing (i) and (ii), we get

[tex]k=\dfrac{9}{2}[/tex]

The constant of proportionality is [tex]\dfrac{9}{2}[/tex]. Therefore, the correct option is B.