Respuesta :

Answer:

y = 40

Step-by-step explanation:

For #7, we are told that y = 10 when x = 2

We are also told that 'y varies directly as x'. That means there is some constant number, k, so that

Formula -->  y = kx

Since y=10 and x= 2, we substitute those numbers into the formula.

We get 10 = k × 2.  

So k has to be 5, right?

k = 5

So what is y when x = 8?

Use the formula.

y=kx ---> That gives us y = k × 8. But we know k is 5.

                                 So y = 5 × 8 = 40

                                       y = 40

sqdancefan

9514 1404 393

Answer:

  7. y = 5x; y = 40

  8. y = 1/3x; y = 8/3

Step-by-step explanation:

In the direct proportion equation y=kx, the value of k can be found as ...

  k = y/x . . . . . divide both sides by x to solve for k

__

7. k = 10/2 = 5

The equation is ...

  y = 5x

For x=8, the value of y is found using the equation:

  y = 5(8) = 40

__

8. Same deal, different numbers.

  k = 6/18 = 1/3

  y = 1/3x . . . . . the equation

  y = 8/3 . . . . . y for x=8

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