z varies directly as x? and inversely as y? If z = 106 when x = 4 and y = 4, find z if x = 9 and y = 8. (Round off your answer to the nearest hundredth.

z varies directly as x and inversely as y If z 106 when x 4 and y 4 find z if x 9 and y 8 Round off your answer to the nearest hundredth class=

Respuesta :

Step 1

Write the joint relationship between z,x and y

[tex]z\text{ }\alpha\text{ }\frac{x^2}{y^2}[/tex]

If we add the constant of proportionality k, we will have;

[tex]z\text{ = }\frac{kx^2}{y^2}[/tex]

Step 2

Find the exact relationship between z,x and y by finding the value of k

[tex]\begin{gathered} z=106 \\ x=4 \\ y=4 \\ 106=\frac{4^2(k)}{4^2} \\ k=\frac{106(4^2)}{4^2} \\ k=106 \end{gathered}[/tex]

Hence the relationship is;

[tex]z=\frac{106x^2}{y^2}[/tex]

Step 3

Find z, if x=9 and y=8

[tex]z=\frac{106(9)^2}{8^2}[/tex][tex]\begin{gathered} z=\frac{8586}{64}=134.15625 \\ z\approx134.16\text{ to the nearest hundredths} \end{gathered}[/tex]

Answer; z = 134.16