Question

Z varies jointly with x and y. when x=-8 and y=-3, z=6. find z when x=2 and y=10.

Answer 1

z = 5

Explanation:

given z varies jointly with x and y then the equation relating them is

z = kxy ← k is the constant of variation

to find k use the condition when x = - 8, y = - 3 and z = 6

6 = k(- 8)(- 3) = 24k ( divide both sides by 24 )

`(6)/(24)` = k , that is

k =
`(1)/(4)`

z =
`(1)/(4)` xy ← equation of variation

when x = 2 and y = 10 , then

z =
`(1)/(4)` × 2 × 10 =
`(1)/(4)` × 20 = 5