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