Question

Find the constant of proportionality for the graph and write in the form y = kx. A) y = 1 7 x B) y = 5x C) y = 7x D) y = 35x

Answer 1

Option C is correct

`y = 7x`

Explanation:

Direct variation states that:

`y \propto x` ......[1]

then, the equation is in the form of:

`y=kx`, where k is the constant of variation

From the given graph we have points in the form of (x, y) i.e,

(0, 0), (5, 35), (10, 70), (15, 105), (20, 140), (25, 175) and (30, 210)

Substitute any points i.e (5, 35) in [1] we have;

`35 = 5k`

Divide both sides by 5 we have;

7 = k

or

k = 7

then;

`y = 7x`

Therefore, the constant of proportionality for the graph is, 7 and its form is,
`y = 7x`

Answer 2

Find the x and y for each dot:

5,35

10,70

15,105

etc.

Divide the Y by the X:

35 / 5 = 7

70 / 10 = 7

etc.

The answer would be C) y = 7x