If y is inversely proportional to x, and y=12 when x=7, find the constant of proportionality and write a formula for y in terms of x?

The formula for inversly proportional is #y=k/x^n#
Use your formula to find x when y is 4?

1 Answer
Jim G.
Nov 16, 2017

#y=84/x#

Explanation:

#"the initial statement is "yprop1/x#

#"to convert to an equation multiply by k the constant"#
#"of variation"#

#rArry=kxx1/x=k/x#

#"to find k use the given condition"#

#y=12" when "x=7#

#y=k/xrArrk=yx=12xx7=84#

#"the equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(y=84/x)color(white)(2/2)|)))#

#"when "y=4#

#y=84/xrArrx=84/y=84/4=21#

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