14th term of an ap is twice its 8th term.if its 6th term is -8,the find the ratio of its first 20terms
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a14 = 2a + 2(8-1)(d)
a14 = 2a + 14d
a + 13 d = 2a + 14d
-a = d
a6 = -8
a + 5d = -8
-d + 5d = -8
4d = -8
d = -2
a = 2
a20 = 2 + 19(-2)
a20 = 2 - 38
a20 = -36
a14 = 2a + 14d
a + 13 d = 2a + 14d
-a = d
a6 = -8
a + 5d = -8
-d + 5d = -8
4d = -8
d = -2
a = 2
a20 = 2 + 19(-2)
a20 = 2 - 38
a20 = -36
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