Question

Which term of the progression 20, 19

4

1

, 18

2

1

, 17

4

3

, ... is the first negative

term

Answer 1

First term a = 20

Common difference d = 19.25 - 20 = -0.75

Let the first negative term be n

Tn = a + (n-1)d

n = 20 + (n-1) *(-0.75) < 0

20 - 0.75n + 0.75 < 0

-0.75n < - 20.75

n > 20.75/0.75

n > 27.6

n = ~28.

.The first negative term is 28.