If y varies directly as x^3 and y=36 when x=7, find y if x=4? (Round answer to the nearest hundredth) , find y if x=4 x = 4 . (Round off your answer to the nearest hundredth.)

I don't understand this at all and need help with it asap for an assignment

1 Answer
Jim G.
May 1, 2018

#~~6.72" to nearest hundredth"#

Explanation:

#"the initial statement is "ypropx^3#

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

#rArry=kx^3#

#"to find k use the given condition"#

#y=36" when "x=7#

#y=kx^3rArrk=y/x^3=36/7^3=36/343larrcolor(blue)"exact value"#

#"equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(y=36/343x^3=(36x^3)/343)color(white)(2/2)|)))#

#"when "x=4" then"#

#y=(36xx4^3)/343=(36xx64)/343=2304/343~~6.72#

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