B(1)=-54
b(n)=b(n-1) 4/3
what is the 4th term

  -128

Step-by-step explanation:

Evaluate the recursive relation 3 times:

  b(2)= b(1) 4/3 = (4/3)(-54) = -72

  b(3) = b(2) 4/3 = (4/3)(-72) = -96

  b(4) = b(3) 4/3 = (4/3)(-96) = -128

The fourth term is -128.

-128

Step-by-step explanation:

b(1) = -54

b(2) = b(1) ⋅ = -72

b(3) = b(2) ⋅ = -96

b(4) = b(3) ⋅ = -128

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