Question =》
Find the Sum 25+28+31+.....+100.
Answers
Answered by
1
Answer:
A=25
d=28−25=3
an=100
an=a+(n−1)d
100=25+(n−1)(3)
100−25=(n−1)(3)
75=(n−1)(3)
75/3=(n−1)
25=(n−1)
25+1=n
26=n
S n =n/2(a+an)
=26/2(25+100)
=13(125)
=1625
Answered by
2
Answer:
a = 25
an = 100
d= 28 - 25 = 3
an = a + (n - 1)d
100 = 25 + (n - 1)3
100 - 25 = (n - 1)3
75 = (n - 1)3
n - 1 = 75/3
n - 1 = 25
n = 25 + 1
n = 26
Sn = n/2 [a + an]
= 26/2 (25 + 100)
= 13(125)
= 1625
Step-by-step explanation:
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