Answer:
D. 8
Step-by-step 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
