I don't know how to find the answer for (3 + 6b + 3b^2). I'm still confused even after my teacher explained it. Could someone break it down for me?

steps below

Step-by-step explanation:

3 + 6b + 3b² = 3 (b² + 2b + 1) = 3 (b + 1)²

root: -1         if 3 + 6b + 3b² = 0               b = -1

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