Question

if the value of "y" varies directly with "x" and y= -8 when x=20, find "y" if x= -4enter the number that belongs in the green box. reduce to the simplest form. y= ?/?

Answer 1

Step-by-step explanation:

Direct variation means that the relation between the two variables is:

`y=kx`

k is called constant of proportionality. To find it we have to replace a pair of values x and y and then solve for k. We're given y = -8 and x = 20:

`\begin{gathered} -8=k\cdot20 \\ k=(-8)/(20)=-(2)/(5) \end{gathered}`

Therefore the relation is:

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

Now, if we replace x = -4:

`y=-(2)/(5)\cdot(-4)=(2\cdot4)/(5)=(8)/(5)`

Answer:

`y=(8)/(5)`