Question

Directions: y varies directly with x. Write an equation for the direct variation. Then find each value. 3. If y = 8 when x = 3, find y when x = 45. 4. If y=-4 when x= 10, find y when x=2. 5. Find y when x = 3 if y=-4 when x = -9. 6. If y= 20 when x = 8, what is the value of x when y=-2?

Answer 1

The value of y when x = 45 is 120

Here, we have a direct variation question

Let us have the constant of variation as k

Since it is a direct variation, the relationship between the two is;

`y\text{ = kx}`

We can find the value of k from the initial values of x and y given

Mathematically, that would be;

`k\text{ = }(y)/(x)\text{ = }(8)/(3)`

Now, we want to find the value of y when is 45

Recall;

`\begin{gathered} y\text{ = kx} \\ \\ y\text{ = }(8)/(3)\text{ }*\text{ 45} \\ \\ y=8\text{ }*\text{ 15 = 120} \end{gathered}`