Question

What is a common difference in the following arithmetic sequence -12,-1,10,21

Answer 1

`a_1=-12\\a_2=-1\\a_3=10\\a_4=21\\\\a_2-a_1=-1-(-12)=-1+12=11\\\\a_3-a_2=10-(-1)=10+1=11\\\\a_4-a_3=21-10=11\\\\Answer:\ \boxed{\text{the common difference d = 11}}`