Question

If y varies directly with x and y=30 when x=5, find y if x=-3

Answer 1

If y varies directly with x then:

y = k x

x = 5 , y = 30

30 = k ∙ 5

30 / 5 = k

6 = k

k = 6

y = 6 x

x = - 3

y = 6 x

y = 6 ∙ ( - 3 ) = - 18

OR

y / x = y / x

30 / 5 = y / ( - 3 )

6 = y / ( - 3 )

Multiply both sides by - 3

- 18 = y

y = - 18

Answer 2

If “x” variation directly as yand x=5 and y=30 find the constant of variation and the equalation of variation