If y varies directly with x, and If y = -36 when x = 6, how do you find x when y = 42?

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If y varies directly with x, and If y = -36 when x = 6, how do you find x when y = 42?

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Answer 1 · 2017-05-25T15:40:50

$x = - 7$ $x=-7$

Explanation:

If y varies directly with x that means:

$y = k x$ $y=kx$

where $k$ $k$ is a constant.

When we say a variable varies directly with another variable, that is another way of saying that if the first variable increases, the second variable increases and vice-versa.

Now, we simple solve for $k$ $k$ and substitute the values of $x$ $x$ and $y$ $y$ to find the constant $k$ $k$ .

$k = \frac{y}{x}$ $k=y/x$

$k = \frac{- 36}{6}$ $k=(-36)/6$

$k = - 6$ $k=-6$

To find $x$ $x$ when $y = 42$ $y=42$ , we will solve for x in the original equation and substitute the values of $k$ $k$ and $y$ $y$ .

$y = k x$ $y=kx$

$x = \frac{y}{k}$ $x=y/k$

$x = \frac{42}{- 6}$ $x=42/-6$

$x = - 7$ $x=-7$

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If y varies directly with x, and If y = -36 when x = 6, how do you find x when y = 42?

1 Answer

Explanation:

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