Question

For the A.P. \[14, 16, 18, \ldots\], which values of a, d and n are used to find the sum of the first 100 terms?

Options

• \[a = 14,\ d = 16,\ n = 99\]

• \[a = 16,\ d = 14,\ n = 100\]

• \[a = 14,\ d = 2,\ n = 100\]

• \[a = 2,\ d = 14,\ n = 100\]

Answer 1

The first term is \[a = 14\] and the common difference is \[d = 16 - 14 = 2.\] The number of terms required is \[n = 100.\] These are substituted in \[S_n = \frac{n}{2}[2a + (n-1)d].\]