Suppose y varies jointly as x & z. If y = -180 when z = 15and x = -3,then find y when x = 7 and z = -5.

y = - 140

Step-by-step explanation:

Given that 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 = - 180 when z = 15 and x = - 3, thus

- 180 = k × - 3 × 15 = - 45k ( divide both sides by - 45 )

4 = k

y = 4xz ← equation of variation

When x = 7 and z = - 5, then

y = 4 × 7 × - 5 = - 140

answer

d. 10

explanation

the distance from point y to wx is the height of the triangle.

using pythagoras theorem,

group similar terms to get,

this implies that,

take positive square root of both sides to get,

this implies that,