If y varies directly with x and y=21 when x=7, how do you find y when x=-1.66?

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If y varies directly with x and y=21 when x=7, how do you find y when x=-1.66?

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Answer 1 · 2018-03-06T21:43:40

$y = - 4.98$ $y=-4.98$

Explanation:

This statement means $y \propto x$ $y propx$ , which can also be written in the form $y = k x$ $y=kx$ when it is directly proportionate and $y = \frac{k}{x}$ $y=k/x$ when inversely proportionate, where $k$ $k$ is a value we need to work out.

Since the equation is in the form $y = k x$ $y=kx$ we know that...

$21 = K \times 7$ $21=K xx 7$

$therefore$ $k=21/7=3$ .

So we can write this as the formula:

$y=3x$

Therefore using the value of $x=-1.66$

$y=3x -> y=3xx -1.66=-4.98$

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If y varies directly with x and y=21 when x=7, how do you find y when x=-1.66?

1 Answer

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