y is directly proportional to x. When x = 4, y= 12.(a) Find the equation of y in term of x. (b) Find the value of y when x=7

see explanation

Step-by-step explanation:

(a)

Given y is directly proportional to x then the equation relating them is

y = kx ← k is the constant of proportion

To find k use the condition when x = 4 , y = 12 , then

12 = 4k ( divide both sides by 4 )

3 = k

y = 3x ← equation of proportion

(b)

When x = 7 , then

y = 3 × 7 = 21

a) y = 3x

b) y = 21

Step-by-step explanation:

a) y = kx

When x = 4, y = 12,

12 = k*4

k = 12/4

  = 3

y = 3x

b) When x=7,

y = 3(7)

= 21

Feel free to mark this as brainliest! :D

i would say the third one.

step-by-step explanation: liner would mean in a line and the only one that doesn't look like it's even thinking about forming a line would be the third one

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional