in an ap,the frist term is 2 and the sum of frist five terms is one fourt of the next five terms .show that its 20th term is-112?
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First term = 2
Let d be the common difference of the A.P.
Therefore, the A.P. is 2, 2 + d, 2 + 2d, 2 + 3d, …
Sum of first five terms = 10 + 10d
Sum of next five terms = 10 + 35d
According to the given condition,
=>10+10d = 1/4(10+35d)
=>40+40d = 10+35d
=>30 = −5d
=>d = −6
∴ a20 = a+(20−1)d = 2+(19)(−6) = 2−114 = −112
Hence, the 20th term of the A.P. is –112.
✌️☺️
Let d be the common difference of the A.P.
Therefore, the A.P. is 2, 2 + d, 2 + 2d, 2 + 3d, …
Sum of first five terms = 10 + 10d
Sum of next five terms = 10 + 35d
According to the given condition,
=>10+10d = 1/4(10+35d)
=>40+40d = 10+35d
=>30 = −5d
=>d = −6
∴ a20 = a+(20−1)d = 2+(19)(−6) = 2−114 = −112
Hence, the 20th term of the A.P. is –112.
✌️☺️
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