Y varies jointly as x and z. If y = 12 when x = 4 and z = 3, find y when x = 9 and z = 8.

y = 72

Step-by-step explanation:

Given y varies jointly as x and z then the equation relating them is

y = kxz ← k is the constant of variation

To find k use the condition y = 12 when x = 4 and z = 3

12 = k × 4 × 3 = 12k ( divide both sides by 12 )

1 = k

y = xz ← equation of variation

When x = 9 and z = 8 , then

y = 9 × 8 = 72

answer

see attachment

explanation

the given function is

this function has y-intercept at

-4 and a slope of 2.

note that, the graph has a positive slope.

the graph that represents this function is the straight line that moves upward from left to right.

the graph touches the y-axis at -4.

the correct choice is the graph shown in the attachment.