The first term of an AP is 7 and the fifth term is 35. Find the sum of its 15th term and
23rd term.
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Step-by-step explanation:
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Answered by
1
Step-by-step explanation:
a = 7
5th term = 35
5th term = a + (n-1)d
35=7+(5-1)d
35-7=4d
28=4d
7=d
sum of 15th term = n/2[2a+(n-1)d]
S=15/2[2*7 + (15-1)7]
S = 15/2[14+98]
S = 15/2*112
S = 15*56
S = 840
23th term = a+22d
23th term = 7+22*7
23th term = 7+154
23th term = 161
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