Question

What is the value of the 19th term in the sequence -1, -5, -9, ...?

Answer 1

-5 -(-1) = -5+1= -4
and
-9 -(-5) = -9+5 = -4

we observe that the number are in AP

of the AP -
ist term = -1
common difference = -4
19th term = -1 + (19-1)(-4)= -1 -72 = -73
_________________________

the correct answer = B

Answer 2

The Arithmetic Sequence formula is:
an = a1 + (n-1)(d) where d is the common difference and a1 is the first term in the sequence.
a19 = -1 + (19 - 1)( -4)
a19 = -1 + (18 * -4)
a19 = -1 + (-72)
a19 = -73
LETTER B