Question

How many terms of AP 24,21,18....must be taken so that their sum is 78.Explain the double answer​

Answer 1

Answer:

-17

Step-by-step explanation:

we have,

a= 24

d= a2-a= 21-24 = -3

n=?

an=78

=>a+(n-1)d=78

=>24+(n-1)(-3)=78

=>(n-1)(-3)= 78-24

=>n-1 = 54/(-3)

=>n-1= -18

=> n= -18+1

=>n= -17

hope it helped you

please follow me and mark as brainliest