Suppose that z varies jointly as u and v and inversely as w, and that z=.8 and when u=8, v=6, w=5. How do you find z when u=3, v=10 and w=5?
1 Answer
Sep 26, 2017
Explanation:
"the initial statement is "zprop(uv)/wthe initial statement is z∝uvw
"to convert to an equation multiply by k the constant"to convert to an equation multiply by k the constant
"of variation"of variation
rArrz=(kuv)/w⇒z=kuvw
"to find k use the given condition"to find k use the given condition
z=0.8" when "u=8,v=6,w=5z=0.8 when u=8,v=6,w=5
z=(kuv)/wz=kuvw
rArrk=(wz)/(uv)=(5xx0.8)/(3xx10)=0.8/6=8/60=2/15⇒k=wzuv=5×0.83×10=0.86=860=215
"equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(z=(2uv)/(15w))color(white)(2/2)|)))
"when "u=3,v=10" and "w=5
rArrz=(2xx3xx10)/(15xx5)=60/75=4/5