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Answers
Answer:
68
Step-by-step explanation:
given
sum of third and seventh term is 6
in a.p the general term is
an = a + (n - 1)d
third term is
》a3 = a + (3 -1)d
》a3 = a + 2d
similarly
seventh term
》a7 = a + 6d
》》a3 + a7 = (a + 2d) + (a + 6d) = 2a + 8d = 6
.......(given)
》2a + 6d = 6
》a + 4d = 3 .....eq 1
also given product is 8
a3*a7 = I
(a + 2d) * (a +6d) = 8
》a^2 + 12d^2 + 8ad = 8 ....eq 2
by squaring (eq 1) and subtracting with (eq 2)
we get
(a^2 + 12d^2 + 8ad) - (a +4d)^2 = 8 - 3^2
》(a^2 + 12d^2 + 8ad) - (a^2 + 16d^ 2 + 8ad) = 8 - 9
》-4d^2 = -1
》d^2 = 1/4
》d = 1/2
substitute this in eq 1
a + 4d = 3
》a + 4*1/2 = 3
》a = 1
sum of first 16 term = sn = n/2 * (a + (n - 1)d)
》s16 = 16/2 * (1 + (16 - 1) * 1/2)
》s16 = 8 * 17/2
》s16 = 68
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Answer:
The answer will be 68.
The above is the correct answer.☺