Question

Calculate the common difference of an arithmetic progression given that its first term is $-6$ and its ${12}^{th}$ term is $126$.

• A. 3
• B. 4
• C. 6
• D. 10
• E. 12

Answer 1

The correct option is E 12

We know, $a_n=a_1+(n-1)d$

Here we have $a_{12}=126,a_1=-6,n=12$

$\Rightarrow 126=-6+(12-1)d$

$\Rightarrow 126=-6+11d$

$\Rightarrow -11d=-6-126$

$\Rightarrow -11d=-132$

$\Rightarrow d=\frac{-132}{-11}=12$