Question

X varies directly with y. if y = -57 when x = 9, find x when y = 27.

Answer 1

x = -81 / 19

Explanation:

y = kx

-57 = 9k

k = -57/9 or -19/3

27 =
`(-19x)/(3)`

-19x = 81

x = -81 / 19

Answer 2

• y1=-57
• x1=9
• y_2=27

`\\ \rm\bull\longmapsto x\propto y`

`\\ \rm\bull\longmapsto x_1y_2=x_2y_1`

`\\ \rm\bull\longmapsto x_2=x_1y_2/ y_1`

`\\ \rm\bull\longmapsto x_2=(9(27))/(-57)`

`\\ \rm\bull\longmapsto x_2=(243)/(57)`

`\\ \rm\bull\longmapsto x_2=-4.26`

`\\ \rm\bull\longmapsto x_2\approx 4`