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If the value of y varies directly with x and y= -1 when x=3, find y if x=9

User Nica
by
8.3k points

2 Answers

2 votes

Answer:

y=-3

Explanation:

y-kx

-1=k(3)

/ /

3 3


(-1)/(3)=k

y=
((-1)/(3))
(9)\\

y=-3

User Yellowantphil
by
8.8k points
4 votes

y = - 3

Since y varies directly as x then

y = kx ← ( k is the constant of variation )

to find k use y = - 1 when x = 3

k =
(y)/(x) =
(-1)/(3) = -
(1)/(3)

hence y = -
(1)/(3) x

when x = 9, then

y = -
(1)/(3) × 9 = - 3


User Jananath Banuka
by
8.6k points

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