In an AP, i

Given:

• d = – 4

• a_{7 =} 4

To find: a (first term)
Explanation:

Now, in an AP we know,

a_n = a + (n – 1)d

Where a_n is the n^th term in the AP, d is the common difference, and a is the first term in the AP.

Putting values in the above equation for n = 7

a₇ = a + 6d

⇒ 4 = a + 6( – 4)
⇒ 4 = a - 24

a = 28

∴ The first term is 28.