Question

Suppose y varies directly as x. Write a direct variation equation that relates x and y. Then solve. If y=6 when x=9 find x when y=12

Answer 1

"something" varies directly to "something else" means
something = (some number) * "something else" or we could say it as
y = (n) * x

what's that number "n"? we dunno
but we know that, when x = 9, y = 6, so if we use that in our equation

\(\bf y = (n) x\qquad \qquad \qquad x = 9\quad y = 6\\ \quad \\
6 = (n) 9\implies 6 = 9n\)

solve for "n" to find what "that number, or the CONSTANT OF VARIATION" is

once you found "n", and you'd like to know what "x" is when y = 12, plug "y" and "n" in the equation, and solve for "x" :)

Answer 2

jdoe...can you just set this up like a proportion ?

Answer 3

yes... but ahe.mm well... is another way to do it... just trying to see which one is more intelligible

Answer 4

is a proportion an equation ? A direct variation one ?

Answer 5

yes it's, yes ahemm well.... it's just a matter of approach.... either method sees it from a feasible angle

Answer 6

you can continue...I am not gonna take over your question.....thanks for clearing that up for me :)

Answer 7

ohh tis ok :), we're here to give a hand, a hand is always welcome