plz tell me answer find n
Attachments:

Answers
Answered by
0
Answer:
a1=12
a2=16
a3=20
d=4
sn=n/2(2a+(n-1)d)
672×2=n(2×12+(n-1)4)
1344=24n+4n^2-4n
1344=20n+4n^2
1344/4=5n+n^2
336=n^2+5n
n^2+5n-336=0
after solve this equation
we get
n=16,-21
then n is 16
marks as brainliest
Similar questions