Zvaries inversely with x and directly with y. when x=6 and y=2 z=5 what is the value of a when x=4 and y=9

        15·9

z = = 135/4

         4

Step-by-step explanation:

The general formula here is as follows:

        ky

z =

         x

We must find the value of the constant of proportionality.  To do this, subst. 6 for x, 2 for y and 5 for z and compute k:

        k·2

5 =

         6

Multiplying both sides by 6 results in 30 = 2k.

Thus, k = 30/2, or k = 15.

Our formula becomes:

        15y

z =

         x

if x = 4 and y = 9, we get:

        15·9

z = = 135/4

         4

Step-by-step explanation:

We are given that z varies inversely with x and directly with y when x=6 and y=2 then z=5

We have to find the value of z when x=4 and y=9

According to question

and

Therefore, we have

k=proportionality constant

Substitute x=6 , y=2 and z=5 then we get

By division  poperty of equality

k=15

Now, substitute the value x=4,y=9 and k=15 then the value of z

step-by-step explanation: