Question

Identify the function in which y varies directly with x.

y = x


y = 9x + 9


y = 0x


y = 9x − 9

Answer 1

The equation in which y varies directly with x is y = x.

This is because no matter what value of x we put in, we get the same y. So when we change x, y changes directly. No other equation has that same fact. As a result, this is the only direct variation.

Answer 2

Option 1st is correct

y = x

Explanation:

The direct variation states:

if
`y \propto x`

then the equation is in the form of:

`y=kx` where, k is the constant of variation and k ≠ 0

As per the statement

Identify the function in which:

y varies directly with x.

By above definition

⇒y = kx

Let k = 1

then, we get the function:

⇒y = x

Therefore, the function in which y varies directly with x is, y = x