Question

If y varies directly with x, and y = 10 when x = 4, write the direct linear variation equation

A. y = 10x

B. y = 4x

C. y = 5/2

D. y = 2/5

Answer 1

The answer is c. I chose the answer c because y=5/2x(I think you forgot to put the x in the question) filled in with the numbers are true while a, b, and d aren't true if filled with 10 and 4.

Answer 2

`y=(5)/(2)x`

Explanation:

Given,

y varies directly with x,

I.e.
`y\propto x`

`\implies y = kx ----(1)`

Where,

k = constant of proportionality,

We have,

y = 10 when x = 4

From equation (1),

`10=4x\implies x = (10)/(4)=(5)/(2)`

Again from equation (1),

`y=(5)/(2)x`

Which is the required direct linear variation equation.