Question 32382
The variable z varies jointly with x and y.
a)write an equation relationg z, x, and y. 
b) if x=2, y=1/8, z=3 then find z when x=3&y=-4 
Z VARIES JOINTLY WITH X AND Y MEANS ...
Z=KXY...WHERE K IS A CONSTANT...{Z VARIES AS X OR VARIES DIRECTLY AS X MEANS 
Z=KX...WHERE K IS A CONSTANT.
Z VARIES INVERSELY AS X MEANS ....Z=K/X...WHERE K IS A CONSTANT...}
X=2,Y=1/8 AND Z=3...
HENCE...3=K*2*1/8=K/4........OR.....K=3*4=12
SO IF X=3 AND Y= -4 THEN
Z=12*3*(-4)= -144