Tuklasin ang mundo ng kaalaman at mga sagot mula sa komunidad sa IDNStudy.com. Sumali sa aming platform ng tanong at sagot upang makakuha ng eksaktong tugon sa lahat ng iyong mahahalagang tanong.

Which term of the arithmetic sequence is -18, given that a1= 7 and a2= 2?

Sagot :

We can determine from here that the common difference is -5 since:
[tex]a_2-a_1=2-7=-5[/tex]
so:
[tex]n= \frac{a_n-a_1}{d} +1= \frac{-18-7}{-5} +1= 6[/tex]
The formula for the arithmetic sequence:
[tex]a_n=a_1+(n-1)d[/tex]

Find the common difference:
2-7=-5

Substitute -18 as [tex]a_n[/tex]
-18=7-5(n-1)
Distribute
-18=7-5n+5
Add like terms
-18=5n+12
Subtract both sides by 12
-30=-5n
Divide both sides by -5
n=6

Hope this helps =)