Question

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

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