Question

The third term of an arithmetic sequence is 42 and seventh term is 66. The common difference of the arithmetic sequence is :

• A. 5
• B. 6
• C. 4
• D. 7

Answer 1

Answer:

B. 6

$a_n=a+(n-1)d$

$a_3=a+2d=42$

$a_7=a+6d=66$

$a+2d=42$

$-a-6d=-66$

$-4d=-24$

$d=6$