Question

Two Aps have the same first and last terms .The first Ap has 21 terms with a common difference of nine how many terms has the other ap if it common difference is 4​

Answer 1

46 terms

Explanation:

a₁=b, a₂₁= bₙ, d₁=9, d₂=4

n=?

---------------

a₂₁= a₁+20d₁= a₁+20*9= a₁+180

bₙ= b₁+(n-1)d₂= a₁+4(n-1)

a₁+4(n-1)=a₁+180

4(n-1)=180

n-1= 180/4

n-1= 45

n=46