Question

Suppose y varies directly as x. If y = 12 when x = 4:

Write the general variation equation
Find the constant of variation, k.
Write a variation equation relating x and y using the value of k found in b).
Find y when x = -5.
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Answer 1

y = -15

Explanation:

Given that,

y varies directly as x i.e.

`y\propto x\\\\y=kx`

Where

k is the constant of variation.

Put y = 12 and x = 4 to find k.

`k=(y)/(x)\\\\k=(12)/(4)\\\\k=3`

Now put k = 3 and x = -5 and finding the value of y.

`y=3* -5\\\\y=-15`

So, the value of y is equal to -15.