Question

which term of an AP 24, 21, 18 ,15 ....is first negative term_____.


and pls also answer how 9 turns to 10.........​

Answer 1

Your answer :

Refer to the attachment!!^^

Answer 2

Solution

a=24

d=21-24=-3

now let the first term which will be a negative term would be n'th term..

now..

and the term is ..

a(n)=24+(n-1)(-3)<0

=>24-3n+3<0

=>-3n<-27

=>3n>27

=> n>9

now the term is greater than of 9 ..

i.e., the first term which will be a negative term is the 10th term.,.

Checking

a(9)=24+(9-1)(-3)=24-24=0

a(10)=24+(10-1)(-3)=-3(first negative number)

Thank u......