Question

find the number of terms in the AP 18, 15 1/2, 13, so on -47​

Answer 1

here,

a=18

d= 15.5-18 = -2.5

tn=-47

tn=a+(n-1)d

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

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

-65=(n-1) -2.5

-65/-2.5 = n-1

26=n-1

n=27