If y varies inversely as X^2 and X = 9 when y = 64, how do you find the value of y when x = 4?

1 Answer
May 2, 2017

Answer:

#y=324#

Explanation:

#"varies inversely means " 1/"variable"#

#rArr"the initial statement is " yprop1/(x^2)#

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

#rArry=kxx1/x^2=k/x^2#

#"to find k, use the condition given"#

#y=k/x^2rArrk=x^2y#

#"given " x=9" when " y=64#

#rArrk=9^2xx64=5184#

#rArr" equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(y=5184/x^2)color(white)(2/2)|)))#

#"when x = 4 then"#

#y=5184/16=324#