Z varies jointly with x and y when x=7 and y=2, z=28. How do you write the function that models each variation and then find z when x=6 and y=4?

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Answer 1 · 2015-06-29T17:37:19

The function is #z = 2xy#. When #x =6# and #y = 4#, #z = 48#.

We know that the function has the form

#z = kxy#, so

#k = z/(xy)#.

If #x = 7#, #y = 2#, and #z = 28#,

#k = 28/(7 × 2)= 28/14 = 2.#

So

#z = 2xy#

If #x = 6# and #y = 4#,

#z = 2 × 6 × 4 = 48#