zz is directly proportional to xx and yy. If when x=6x=6 and y=8y=8, then z=48z=48, then what is zz, when x=10x=10 and y=12y=12?

2 Answers

z=120z=120

Explanation:

zz varies jointly as xx and yy means zpropxzx and zpropyzy i.e.

zpropx xxyzx×y

In other words z=kxx xyz=k×xy where kk is a constant

Since when x=6x=6 and y=8y=8, w have z=48z=48, we have

48=kx6xx848=kx6×8 and k=48/(6xx8)=48/48=1k=486×8=4848=1

and hence z=xyz=xy

and when x=10x=10 and y=12y=12

z=10xx12=120z=10×12=120

Jun 14, 2017

z=120z=120

Explanation:

"the initial statement is " zpropxythe initial statement is zxy

"to convert to an equation multiply by k the constant of"to convert to an equation multiply by k the constant of
"variation"variation

rArrz=kxyz=kxy

"to find k use the condition given for x, y and z"to find k use the condition given for x, y and z

x=6,y=8" when " z=48x=6,y=8 when z=48

z=kxyrArrk=z/(xy)=48/(6xx8)=1z=kxyk=zxy=486×8=1

rArr" equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(z=xy)color(white)(2/2)|)))

"when " x=10" and " y=12

z=10xx12=120