Question

Which term of sequence 20, 19 1/4, 18 1/9, 17 3/4,..... is the first negative term?

Answer 1

It's a decreasing sequence. Let's find the number of term which will be zero. Then the next integer will give negative term.

answer and equating an to zero.

a = 20 , d = -3/4

an = a+(n-1)d

= 20+(n-1)(-3/4)

= 20+(-3n+3)/4

= (80-3n+3)/4

83 - 3n = 0

3n - 83 = 0

n = 83/3

n = 27.66

The next integer is 28

So 28th term will be the first -ve term....