Question 1149574
If x varies as the square of y and inversely as z 
<pre>
Whatever comes after "varies as" is multiplied by k and goes on top, 
and what comes after "inversely as" goes on the bottom.

{{{matrix(1,3,x,""="",(k*y^2)/z^"")}}}</pre>and x=12 when y=3 and z=6,<pre>
Substitute and solve for k

{{{matrix(1,3,12,""="",(k*(3)^2)/(6)^""))}}}

{{{matrix(1,3,12,""="",(k*(9))/6))}}}

{{{matrix(1,3,12,""="",9k/6)}}}

Multiply both sides by 6

{{{matrix(1,3,72,""="",9k)}}}

{{{matrix(1,3,8,""="",k)}}}

Substitute 8 for k in the original variation equation:

{{{matrix(1,3,x,""="",(8*y^2)/z^"")}}}</pre>find x when y=9 and z=6.<pre>Substitute the new values for y and z

{{{matrix(1,3,x,""="",(8*9^2)/6^"")}}}

{{{matrix(1,3,x,""="",(8*81)/6)}}}

{{{matrix(1,3,x,""="",108)}}}

Edwin</pre>