28. Which term of the A.P.
20,19 1/4, 181/2 , 173/4 ... is the first negative term.
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Answer:
-1/4
Explanation:
a = 20
d = -3/4
an = a+(n-1)d
an = 20+(n-1)(-3/4)
an = 20 - 3n/4 + 3/4
an = 20 3/4 - 3n/4
an = (83-3n)/4
an<0
(83-3n)/4 < 0
83 - 3n < 0x4
83 - 3n < 0
83 < 3n
n least value is 28
=> an = (83 - 3n)/4 = (83-84)/4 = -1/4
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