Question

Find the first term of an arithmetic progression, if its $7^{th}$ term is 4 and common difference is -4.

• A. 7
• B. 20
• C. 28
• D. 27

Answer 1

The correct option is C

28

Given that
$a_n$ = 4 , $n=7$ and $d=-4$

General term of an A.P is
$a_n=a_1+(n-1)d$
$\Rightarrow 4=a_1+(7-1)(-4)$
$\Rightarrow 4=a_1-24$
$\Rightarrow a_1=28$

$\therefore$ the first term of the given AP $=28$