Answer:
a9=17
Step-by-step explanation:
Formula: an= a1 + (n-1)d
Given: a9=(-15,-11,-7,-3)
an= 9
a1= -15
d= 4
Substitute:
a9= -15 + (9-1)(4)
a9= -15 + 32
a9= 17
How to get the difference(d)?
subtract second term( a2) to the first term(a1)
Hope it helps!! <333
