Answer:
48
Step-by-step explanation:
It's an arithmetic sequence with common difference d = 7.
[tex]a_1=-8\\\\a_2=-8+7=-1\\\\a_3=-1+7=6\\\\a_4=6+7=13[/tex]
Find 9th term.
METHOD 1.
Calculate next terms:
[tex]a_5=13+7=20\\\\a_6=20+7=27\\\\a_7=27+7=34\\\\a_8=34+7=41\\\\a_9=41+7=48[/tex]
METHOD 2.
The explicit formula of an arithmetic sequence:
[tex]a_n=a_1+(n-1)d[/tex]
Substitue:
[tex]a_n=-8+(n-1)(7)[/tex] use the distributive property
[tex]a_n=-8+7n-7\\\\a_n=7n-15[/tex]
Put n = 9:
[tex]a_9=7(9)-15=63-15=48[/tex]
