Me. these are very confusing.

Step-by-step explanation:

The way you have written the first question may be what is confusing you. It should be written as

bn = 3*b_(n-1) + 2

So b2 =

b2 =3*b_(2 -1) + 2

b2 = 3*b1 + 2

b2 = 3*5 + 2

b2 = 15 + 2

b2 = 17

b3 = 3b_(n _1) + 2

b_2 = 17 (from the step above)

b3 = 3*17 + 2

b3 = 51 + 2

b3 = 53

b_4 = 3*b_3 + 2

b_4 = 3*53 + 2

b_4 = 159 + 2

b_4 = 161

Do you see how this works? You take the previous term, multiply by 3 and add 2 to get the current term. This one builds up rather quickly.

Next Question

tn = a + (n - 1)*d

t6 = a + (6 - 1)*d

t4 = a + 5d

4 = a + 5d    

t10 = a + 9d

Subtract t4 [4 = a + 3d ] from t10 written bellow

- 4 = a +  9d

4  = a + 5d

- 8 = 4d              Divide by 4

-8/4 = 4d/4

-2 = d

t6 = a + 5d

4 = a + 5*(-2)

4 = a - 10               Add 10 to both sides.

4 + 10 = a - 10 + 10

14 = a

tn = 14 + (n - 1)*d

d

Please don't use red. It is really hard to read.