the 3rd term of an AP is -11 and 14 th term of AP is +44 find the 20th term
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3rd term = a + (3-1)d = a + 2d = -11
14th term = a + (14-1)d = a + 13d = 44
on subtracting 1st equation from second equation,
11d = 55
=> d = 55/11
=> d = 5
=> a = -11-2(5) = -11-10 = -21
Now, a20 = a + (20-1)d
=> a20 = a +19d
=> a20 = -21 + 19 (5)
=> a20 = -21 + 95
=> a20 = 74
Thus, 20th term is 74.
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