What is the sum of the first 30 terms of an AP whose nth term
is given by 9 - 4n?
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Answer:An=9-4n
if n=1 ,then A1=5
if n=2,thenA2=1
So d=A2-A1=-4
S30=n/2[2a+(n-1)d]
=30/2[2 x 5 +(30-1)-4]
=15[10+(-116)]
=15 x (-106)
=1590
Step-by-step exlanation:
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