Question

Two A.P.'s are given 9,7,5,.... and 24,21,18,... If nth term of both the progressions are equal then find the value of n and nth term?

Answer 1

an = tn( 'a' is 1st sequence and 't' is 2nd sequenc e)
a1+(n-1)d1 = a2+(n-1)d2

1st AP a1=9, d1 =- 2
2nd AP a2= 24 , d2= -3

9+(n-1)(-2) = 24+(n-1)(-3)
9-2n+2 = 24 -3n + 3
n = 16