Question

If z varies directly with he product of x and y, then z is said to vary __________ with x and y.

Answer 1

@Nnesha
@DanJS

Answer 2

Is this direct variation?

Answer 3

\[z~~\alpha~~x*y\]

Answer 4

So
z = (constant)*x*y

z = k*x*y

Answer 5

so directly?

Answer 6

@dtan5457 go here http://www.shelovesmath.com/algebra/beginning-algebra/direct-inverse-and-joint-variation/ this helps me alot

Answer 7

I would assume, but the question already says ' z varies directly with he product of x and y' so is there some other special word they call it?

Answer 8

Joint variation is just like direct variation, but involves more than one other variable.

Answer 9

Not sure...just started learning this today

Answer 10

Joint

Answer 11

jointly i guess

Answer 12

z varies JOINTLY with x and y

Answer 13

found it on that site jordan linked, didn't know there was a special name for that

Answer 14

Can you quickly explain the difference between jointly and directly?

Answer 15

Joint is where the dependent variable (z) varies directly with more than 1 independent variable, here (x and y)

Answer 16

same as direct variation, just more than 1 independent variable

Answer 17

so z=x (direct)
z=xy (jointly)

Answer 18

direct=1 variable

Answer 19

Direct Variation

\[z~~\alpha~~x\]
\[z = k*x\]

Joint Variation
is a form of direct variation, but z will be directly proportional to more than 1 variable, x and y.

Answer 20

\[z~~\alpha~~x*y\]
\[z = k*(x*y)\]

Answer 21

sorry the site server is bogged down or something, lagging like crazy

Answer 22

Not z = x

\[z~~\alpha~~~x\]
z is proportional to x, you need a constant of proportionality to make an equation

z = k*x

Answer 23

Z varies Directly with X --- z = k*x

Z varies Jointly with x and y ----z = k*x*y

Joint is just a fancy word meaning z varies directly with more than 1 other variable

Answer 24

combined variation 0r joined variation
for example
jz varies jointly with x and y ^^^^
\(\huge\color{green}{{\rm z }=k xy ~}\)
but remember jointly is always in applied direct relation
so if there is a word "jointly" its mean direct

Answer 25

uh-oh lost the connection....trying to reconnect now.
again again agian