Posted by So Confused on .
Find the equation of variation in which y varies jointly as x and z and y=8, x=4 and z=2

College Algebra 2 
Steve,
if a varies directly with b, then it means
a = k*b
If y varies jointly as x & z, then it means y = k * x * z
So, if 8 = k * 4 * 2
Then k = 1, and y = x*z