A.P is 9,4,-1 find sum of 31
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Answered by
1
first term =9
common difference = 4-9=-5
Sn= n/2(2a+(n-1)d)
S31=(31/2)[18+30×(-5)]
= (15.5)[18-150]
=15.5×(-132)=-2046
common difference = 4-9=-5
Sn= n/2(2a+(n-1)d)
S31=(31/2)[18+30×(-5)]
= (15.5)[18-150]
=15.5×(-132)=-2046
Answered by
1
sum of first 31 term
sn=n/2(2a + (n-1)d)
s 31 = 31/2 (2*9 + (31-1) (-5))
s 31= 31/2 (-132)
s 31 = 31 * -66
s 31= -2406
s 31=- 2046
hope it helps!!!!
sn=n/2(2a + (n-1)d)
s 31 = 31/2 (2*9 + (31-1) (-5))
s 31= 31/2 (-132)
s 31 = 31 * -66
s 31= -2406
s 31=- 2046
hope it helps!!!!
swathika23:
thx for marking brainliest!!
sum can be negative
area is never negative
when u add -1+(-1) answer will be -2 not +2
ok
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