Question

The ${30}^{th}$ term in the AP $10,7,4,.$ is

• A. $97$
• B. $77$
• C. $-77$
• D. $-87$

Answer 1

The correct option is C $-77$

$a=10,d=7-10=4-7=-3$

${30}^{th}$ term $t_{30}=10+(30-1)(-3)$ using the formula $t_n=a+(n-1)d$

$\therefore t_{30}=10+\left(29\right)(-3)$

$=10-87=-77$

$\therefore {30}^{th}$ term is $-77$