Question

If y varies jointly as x and z and y = 12 when x = -2 and z=3, find y when x is 4 and z is -1

A. 6
B. 9
C. 4
D. 8​

Answer 1

D. 8​

Explanation:

y varies jointly as x and z

y = k(xz)

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Find k, the constant of variation

y = 12 when x = -2 and z=3

12 = k(-2 * 3)

12 = k(-6)

k = -2

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find y when x is 4 and z is -1

using k = -2

y = -2(4 * -1)

y = -2(-4)

y = 8