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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?

Directions: y varies directly with x. Write an equation for the direct variation. Then-example-1
User Nafis Abdullah Khan
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1 Answer

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22 votes

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}

User Reza Farshi
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