Question

The sum of the first and third term of an arithmetic progression is 12 and the product of first and second term is 24, then first term is.

• A. 1
• B. 8
• C. 4
• D. 6

Answer 1

Answer: (C)

4

Answer 2

Let first 3 terms be $a - d , a$and $a + d$

Now $( a - d ) + ( a + d ) = 12$ $\Rightarrow$ $2 a = 12$

$\Rightarrow$ $a = 6$ and $( a - d ) a = 24$ ⇒ $6 ( 6 - d ) = 24$

⇒ $d = 2$

∴First term = $a - d = 6 - 2 = 4$.