Question

Find the indicated term of the given arithmetic sequence.

a[1]=45, d=-6, n=8

a. 309
b. -3
c. 3
d. 87

Answer 1

`a_n=a_1+(n-1)d\\\\a_1=45;\ d=-6\\\\a_n=45+(n-1)\cdot(-6)=45-6n+6=51-6n\\\\\boxed{a_n=51-6n}\\\\n=8\\\\a_8=51-6\cdot8=51-48=3\\\\\boxed{a_8=3}\to\fbox{c.}`