Suppose that y varies directly with x and inversely with z, y=18 when x=15 and z=5. How do you write the equation that models the relationship, then find y when x=21 and z=7?
1 Answer
Apr 1, 2018
Explanation:
#"the initial statement is "ypropx/z#
#"to convert to an equation multiply by k the constant"#
#"of variation"#
#rArry=kxx x/z=(kx)/z#
#"to find k use the given condition"#
#y=18" when "x=15" and "z=5#
#y=(kx)/zrArrk=(yz)/x=(18xx5)/15=6#
#"equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(y=(6x)/z)color(white)(2/2)|)))#
#"when "x=21" and "z=7" then"#
#y=(6xx21)/7=18#
