Question

Find the number of terms in each of the following APs:
18,15 1/2 ,13.........-47​

Answer 1

a=18. (first term)

d=-3. (common difference)

a^n= -47 ( term)

n=? ( no. of terms)

sol:a^n=a+ (n-1)d

-47=18+(n-1)-3

-47-18=(n-1)-3

-65÷-3= n-1

65/3+1= n

68/3= n

hence the given AP is wrong as n is not an integer