If y varies directly as x and y = 3 when x = - 9, then find x when y = 5.

a. 15

b. 1/15

c. - 1 / 15

d. - 15

Question

Teagan Mejia

Mathematics

12 February, 04:37

If y varies directly as x and y = 3 when x = - 9, then find x when y = 5.

a. 15

b. 1/15

c. - 1 / 15

d. - 15

+2

Answers (1)

Know the Answer?

Maribel Wells · Answer 1

d. - 15

Step-by-step explanation:

The equation for direct variation is

y = kx

We know y = 3 when x = - 9

3 = k (-9)

Divide by - 9

3/-9 = - 9k/-9

-1/3 = k

The equation is then

y = - 1/3 x

We know y = 5

5 = - 1/3 x

Multiply each side by - 3

-3*5 = - 3*-1/3x

-15 = x

If y varies directly as x and y = 3 when x = - 9, then find x when y = 5.a. 15b. 1/15c. - 1 / 15d. - 15

If y varies directly as x and y = 3 when x = - 9, then find x when y = 5.

a. 15

b. 1/15

c. - 1 / 15

d. - 15