1) If y=4 when x = - 2, find x when y = - 5

2) If y=20 when y = - 5, find x when y = - 1

Use direction variation formula

1) x = 2.5 when y = - 5

2) x = 0.25 when y = - 1

Solution:

Given that, we have to use direction variation formula.

Now, we know that, direct variation formula is y = kx, where k is proportionality constant.

1) If y=4 when x = - 2, find x when y = - 5

Put y = 4 and x = - 2 in y = kx

4 = k (-2)

k = - 2

Then, when y = - 5

-5 = ( - 2) x

x = 5/2

x = 2.5

2) If y=20 when x = - 5, find x when y = - 1

Put y = 20 and x = - 5 in y = kx

20 = k (-5)

k = - 4

Then, when y = - 1

-1 = ( - 4) x

x = 1/4

x = 0.25

Hence, 1) x = 2.5 when y = - 5 and 2) x = 0.25 when y = - 1