find the sum of the series 72+70+68+...........+48
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hope u understood :-)
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Jaswant51:
i think it is wrong answer
a (first term ) = 72
d (common difference ) = 70-72 =-2
L (last term ) tn = 48
tn = a + (n-1)d
tn = 72 + (n-1)-2
48= 72 -2n + 2
48 - 74 = -2n
-26 = -2n
n = 13
sn = n/2(a+l)
s13 =13/2(72 + 48)
s13 = 120×13/2 = 60×13
=> 780 Answer
d (common difference ) = 70-72 =-2
L (last term ) tn = 48
tn = a + (n-1)d
tn = 72 + (n-1)-2
48= 72 -2n + 2
48 - 74 = -2n
-26 = -2n
n = 13
sn = n/2(a+l)
s13 =13/2(72 + 48)
s13 = 120×13/2 = 60×13
=> 780 Answer
Answered by
2
Hey !!!
a (first term ) = 72
d (common difference ) = 70-72 =-2
L (last term ) tn = 48
tn = a + (n-1)d
tn = 72 + (n-1)-2
48= 72 -2n + 2
48 - 74 = -2n
-26 = -2n
n = 13
sn = n/2(a+l)
s13 =13/2(72 + 48)
s13 = 120×13/2 = 60×13
=> 780 Answer
***********************************
Hope it helps you !!!
@Rajukumar111
a (first term ) = 72
d (common difference ) = 70-72 =-2
L (last term ) tn = 48
tn = a + (n-1)d
tn = 72 + (n-1)-2
48= 72 -2n + 2
48 - 74 = -2n
-26 = -2n
n = 13
sn = n/2(a+l)
s13 =13/2(72 + 48)
s13 = 120×13/2 = 60×13
=> 780 Answer
***********************************
Hope it helps you !!!
@Rajukumar111
wooooooow
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