Question

WILL AWARD MEDALS

The first term of an arithmetic sequence is -5, and the tenth term is 13. Find the common difference.

A. 8/9
B. 1.8
c. 2

I think its B, but I am not 100% sure

Answer 1

\[a,a+d.a+2d,a+3d,...,a+9d\]
\[-5,-5+d,-5+2d,-5+3d,...,-5+9d=13\] solve
\[-5+9d=13\] for \(d\)

Answer 2

you do not get \(1.8\) though

Answer 3

\[a_1 = -5~~~~and ~~~~a_{10} = 13\]
u must be knowing tht \[a_n = a_1 + (n - 1)d\]
so
\[a_{10} = a_1 + (10 - 1)d\]
\[13 = -5 + 9d\]
solve and get "d"

Answer 4

Thanks :)