If y varies directly with x, find the value of y when x = 27 for the direct variation with the given information. y = 7 when x = -9 y =

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Mathematics Xavia 3 years 2021-08-21T16:11:14+00:00 2021-08-21T16:11:14+00:00 1 Answers 3 views 0

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Captcha* Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )

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Philomena · Answer 1 · 2021-08-21T16:13:11+00:00

Given:

y varies directly with x,

It is given that y = 7 when x = -9.

To find:

The value of y when x = 27 for the direct variation.

Solution:

It is given that y varies directly with x, so

$y\propto x$

$y=kx$ …(i)

Where, k is the constant of proportionality.

It is given that y = 7 when x = -9. Putting these values in (i), we get

$7=k(-9)$

$-\dfrac{7}{9}=k$

Putting $k=-\dfrac{7}{9}$ in (i), we get

$y=-\dfrac{7}{9}x$

Putting $x=27$ , we get

$y=-\dfrac{7}{9}(27)$

$y=-21$

Therefore, the required value is $y=-21$ .