The pattern of the sequence is :
4 × 2 + 1 = 9
9 × 2 + 1 = 19
19 × 2 + 1 = 39
39 × 2 + 1 = 79
........... and so on.

Correct Option: A

The pattern of the sequence is :
4 × 2 + 1 = 9
9 × 2 + 1 = 19
19 × 2 + 1 = 39
39 × 2 + 1 = 79
79 × 2 + 1 = 159 ≠ 169
Since , 169 is wrong number. So , correct number is 159 .

The pattern of the sequence is :
First term = 51
51 + 1² = 51 + 1 = 52
52 + 2² = 52 + 4 = 56
56 + 3² = 56 + 9 = 65
65 + 4² = 65 + 16 = ?

Correct Option: D

The pattern of the sequence is :
First term = 51
51 + 1² = 51 + 1 = 52
52 + 2² = 52 + 4 = 56
56 + 3² = 56 + 9 = 65
65 + 4² = 65 + 16 = ?
∴ ? = 81
Thus , the next number of the sequence is 81 .

The pattern of the sequence is :
5 × 3 = 15
15 × 3 = 45
45 × 3 = 135
........... and so on.

Correct Option: A

The pattern of the sequence is :
5 × 3 = 15
15 × 3 = 45
45 × 3 = 135
135 × 3 = 405 ≠ 395 , Since 395 is wrong number . So , 405 is correct number .
405 × 3 = 1215
Thus , option A is required answer .

The pattern of the sequence is :
1³ + 1 = 1 + 1 = 2
2³ + 1 = 8 + 1 = 9
3³ + 1 = 27 + 1 = 28
4³ + 1 = 64 + 1 = 65
5³ + 1 = 125 + 1 = 126
6³ + 1 = 216 + 1 = ?

Correct Option: D

The pattern of the sequence is :
1³ + 1 = 1 + 1 = 2
2³ + 1 = 8 + 1 = 9
3³ + 1 = 27 + 1 = 28
4³ + 1 = 64 + 1 = 65
5³ + 1 = 125 + 1 = 126
6³ + 1 = 216 + 1 = ?
⇒ ? = 217
Therefore . Next number of the sequence is 217 .

The pattern of the given number series is :
5 + 1² = 5 + 1 = 6
6 + 3² = 6 + 9 = 15
15 + 5² = 15 + 25 = ?
∴ ? = 40
........... and so on.

Correct Option: B

The pattern of the given number series is :
5 + 1² = 5 + 1 = 6
6 + 3² = 6 + 9 = 15
15 + 5² = 15 + 25 = ?
∴ ? = 40
40 + 7² = 40 + 49 = 89
89 + 9² = 89 + 81 = 170
Thus , the missing number in the sequence is 40.