Question

Please help me

Answer 1

Your answer is D. plug 18 into the equation and you'll get 55. if you try to plug in any other number from A,B,OR C, you will not get the answer

Answer 2

Answer: Option 'D' is correct.

Step-by-step explanation:

Since we have given that

$a_1=5$

and

$a_n=(-1)^n+3a_{n-1}+2$

We have to find the first four terms of the sequence :

For n = 2,

$a_2=(-1)^2+3a_{2-1}+2\\\\a_2=1+3a_1+2\\\\a_2=1+3\times 5+2\\\\a_2=1+15+2=18$

For n = 3,

$a_3=(-1)^3+3a_{3-1}+2\\\\a_3=-1+3a_2+2\\\\a_3=-1+3\times 18+2\\\\a_2=-1+54+2=55$

For n = 4,

$a_4=(-1)^4+3a_{4-1}+2\\\\a_4=1+3a_3+2\\\\a_4=1+3\times 55+2\\\\a_2=1+165+2=168$

So, the first four terms of the sequence is given by

$5,18,55,168$

Hence, Option 'D' is correct.