If y varies inversely as x and y = 725 when x = 20, how do you find x when y is 50?

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Answer 1 · 2017-01-04T23:04:28

$x = 290$ $x=290$ when $y = 50$ $y=50$

When you are told that $y$ $y$ varies inversely as $x$ $x$ , that means that

$x \cdot y = k$ $x*y=k$

where $k$ $k$ can be any single number. If you plug in the initially given numerical values for $x$ $x$ and $y$ $y$ you have

$20 \cdot 725 = 14500$ $20*725=14500$

So your $k$ $k$ -value becomes $14500$ $14500$ . Now you can say that, for this particular relation

$x y = 14500$ $xy=14500$

If you want to know your $x$ $x$ -value when $y = 50$ $y=50$ , you can plug $50$ $50$ in for $y$ $y$ and solve for $x$ $x$ .

$x \cdot 50 = 14500$ $x*50=14500$

so

$x = \frac{14500}{50}$ $x=14500/50$

meaning that

$x = 290$ $x=290$ .