Question

3. In an A.P., the first term is 2 and the sum of the first five terms is one-fourth of
the next five terms. Show that 20th term is -112.
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Answer 1

In an AP a1=2, the sum of the first fifth term is 1/4th of the sum of the next five term. What is S20 equal to?

a=2 given

here is your answer

Let d be the common ratio

Terms are a, a+d, a+2d, a+3d a+4d,

a+5d, a+6d , a+7d, a+8d , a+9d

Sum of first five terms=5a+10d=5×2+10d=10+10d

Sum of next 5 terms =a+5d+a+6d+a+7d+a+8d+a+9d=5a+35d

=5×2+35d=10+35d

ATA:

10+35d=4(10+10d)

10+35d=40+40d

10–40=40d-35d

-30=5d

d=-30/5=--6

S20=20/2(2a+19d)

=10(2×2+19×-6) =10(4–114) =10(-110) =-1100

.. Answer

Answer 2

Answer:

answer for the given problem is given