Quadratic patterns, sums and geometric sequences

Answer: 128

1. The second difference is 10
2. a=5.
3. The first term gives b=3.
4. Then u5​=25×5+3.

Answer: 9

1. Solve 3+(n−1)4=35.
2. This gives n=9.

Answer: 154

1. The second difference is 12
2. a=6.
3. The first term gives b=4.
4. Then u5​=25×6+4.