Question

MEDAL + FANNN AWAITINGGGGG


In a direct variation, y is -18 when x is 9. What is y when x equals -6?

-12
-3
3
12

Answer 1

hint:
direct variation between two variables \(x,y\), can be modeled by this formula:
\(y=kx\)

Answer 2

im confused

Answer 3

If I replace \(y=-18\) and \(x=9\), I get:
\(-18=2\cdot k\)
what is the value of \(k\)?

Answer 4

-9

Answer 5

perfect!
so, we can write this \(y=-2x\)
now, please replace \(x=-6\), what is the value for \(y\)?

Answer 6

hint:
\(y=-2x=-2 \cdot (-6)=...?\)

Answer 7

sorry I made an error, here is the right formula:
\(-18=9 \cdot k\), so: \(k=-2\)

Answer 8

i dont understand

Answer 9

hence:
\[\huge y = - 2x = - 2 \cdot \left( { - 6} \right) = ...?\]

Answer 10

after I replace y=-18 and x=9, I get:
\(-18=9k\)
from which, the value of k is \(k=-2\)
so, the formula fo direct variation is:
\(y=-2x\)
now, if I replace \(x=-6\) I get:
\[y = - 2x = - 2 \cdot \left( { - 6} \right) = ...?\]
so, what is the value of \(y\) ?

Answer 11

for*

Answer 12

12

Answer 13

wait is that the answer

Answer 14

that's right!

Answer 15

thank you

Answer 16

it is the value you have found: \(y=12\)

Answer 17

:)