Question

Find number of terms in following sequencs 18, 31/2,13,..-47

Answer 1

Answer:

Step-by-step explanation:

The given AP is

18,\frac{31}{2},13,...,-47

Here the first term is 18 and the common difference is

\frac{31}{2}-18=\frac{31-36}{2}=\frac{-5}{2}=-2.5

The nth term of an AP is

a_n=a+(n-1)d

-47=18+(n-1)(-2.5)

-47=18-2.5n+2.5

-47=21.5-2.5n

-47-20.5=-2.5n

-67.5=-2.5n

Divide both sides by -2.5.

27=n