If y=21 when x=-6, how do you find x when y=7 given that y varies inversely as x?

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If y=21 when x=-6, how do you find x when y=7 given that y varies inversely as x?

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Answer 1 · 2017-07-27T10:31:43

$x = - 18$ $x=-18$

Explanation:

$the initial statement is y \propto \frac{1}{x}$ $"the initial statement is "yprop1/x$

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

$\Rightarrow y = k \times \frac{1}{x} = \frac{k}{x}$ $rArry=kxx1/x=k/x$

$to find k use the given condition$ $"to find k use the given condition"$

$y = 21 when x = - 6$ $y=21" when "x=-6$

$y = \frac{k}{x} \Rightarrow k = y x = 21 \times - 6 = - 126$ $y=k/xrArrk=yx=21xx-6=-126$

$"equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(y=-126/x)color(white)(2/2)|)))$

$"when "y=7$

$x=-126/y=-126/7=-18$

Answer 2 · 2017-07-27T10:32:26

$x= -18$

Explanation:

$y prop 1/x or y = k*1/x or x*y = k ; k$ is constant of proportionality.

$y=21 . x= -6 :. k = x* y =-6 * 21 = -126$ .

So the variation equation is $x * y = -126 ; y=7, x = ?$

$:. x * 7 = -126 :. x = -126/7 = -18$

$x= -18$ [Ans]

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If y=21 when x=-6, how do you find x when y=7 given that y varies inversely as x?

2 Answers

Explanation:

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