if y=4 when x=-2. find x when y=-5

if y=20 when x=-5. find x when y=-1

Step-by-step explanation:

1)If y=4 when x=-2. Find x when y=-5

This is assumed to be a direct proportion. It means that x is directly proportional to y. To make x to be equal to y, that is, removing the "proportionality" sign and replacing it with the "equal to" sign, we will introduce a proportionality constant, k. Therefore,

x = ky - - - - - - - 1

Therefore, we would find the value of k. From the information given,

y=4 when x= -2. Therefore, we will substitute y= 4 and x = -2 in equation 1

-2 = 4k

k = -2/4 = -1/2

x = -1/2 × y = -y/2 - - - - - - - -2

We want to find x when y=-5

Substituting y= -5 in equation 2,

x = - -5/2 = 15/2

2) If y=20 when x=-5. Find x when y= -1

We would follow same procedure above.

x = ky - - - - - - - 1

Therefore, we would find the value of k. From the information given,

y=20 when x=-5. Therefore, we will substitute y= 20 and x = -5 in equation 1

-5 = 20k

k = -5/20= -1/4

x = -1/4 × y = -y/4 - - - - - - - -2

We want to find x when y=-5

Substituting y= -5 in equation 2,

x = - -5/4 = 5/4

x=4

step-by-step explanation: