Q. The sum of the first and third term of an arithmetic series is 12 and the product of first and second term is 24, then first term is
A) 1
B) 8
C) 4
D) 6
Explanation
(c)
Let the first three terms of an AP are $a - d,\ a$ and $a + d$
Since, $(a - d) + (a + d) = 12$
$\Rightarrow \ a = 6$
and $a(a - d) = 24$
$\Rightarrow \ 6 - d = 4$
$\Rightarrow \ d = 2$
$\therefore$ First term is $a - d = 4$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.