Which Term Of The Arithmetic Sequence Is -18, Given That A1=7 And A2= 2

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

 

Answer:

n=6

Step-by-step explanation:

d=2-7=-5

a1=7

an=-18

n=?

an=a1+(n-1)d

-18=7+(n-1)(-5)

-18=7-5n+5

-18=-5n+12

-12 both sides

-30=-5n

Divide -5 both sides

n=6