What is the sum of the arithmetic sequence 174, 168, 162 …, if there are 35 terms?

Question

anonymous · Answer

Actually .. I need more help with this one? A monument is built out of toothpicks. There are 25 rows and each row has eight more toothpicks than the row above. The top row has five toothpicks. How many toothpicks are on the bottom row? Using complete sentences, explain the procedure taken to answer this question.

anonymous · Answer

Do you understand ven?

anonymous · Answer

a1=174
a2=168
d=a2-a1
d=168-174=-6
Sn=n/2(2a+(n-1)d)
S35=35/2(2*174+34(-6)
=17.5(348-204)
=2520

anonymous · Answer

@Serena:Looking at those.

anonymous · Answer

So, there are 25 rows
Last row=l=5 toothpicks...
You know there's a formula somewhere.. I don't remember it though :( sorry..