If the first term of an A.P. is 5 and the common difference is 7, then the first four terms are:

Correct answer: 5, 12, 19, 26. Adding 7 each time gives 5, 12, 19, 26.

Background: In an A.P., each term is the previous term plus the common difference.

• 4, 11, 18, 24: The first term is 5, not 4.
• 5, 13, 20, 27: 13 is not 5 + 7.
• 5, 11, 17, 24: 11 is not 5 + 7.

Did you know? The terms are a, a + d, a + 2d, a + 3d.

Memory trick: Keep adding 7.