SOLUTION: I need some help with this question- I missed the unit lesson and I am having trouble getting the answer. Given that in an arithmetic sequence t3=-2 and t7=-5, what is the for

Algebra ->  Sequences-and-series -> SOLUTION: I need some help with this question- I missed the unit lesson and I am having trouble getting the answer. Given that in an arithmetic sequence t3=-2 and t7=-5, what is the for      Log On


   

Question 77692: I need some help with this question- I missed the unit lesson and I am having trouble getting the answer.
Given that in an arithmetic sequence t3=-2 and t7=-5, what is the formula for the nth term tn? what is the value of t11
Thanks so much
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
an arithmetic sequence means that the difference (d) between consecutive terms is a constant

t3 and t7 are four terms apart so they are 4d apart...4d=-3...d=-3/4

to find any term in the sequence, you just multiply the number of the term minus 1 (n-1) by d and add it to the first term (t1)

tn=t1+(n-1)d...in this problem, t1=t3-2d...or t1=-1/2...so tn=(-1/2)+(n-1)d...so t11=(-1/2)+10(-3/4)...or t11=-8