If the n th term of the A.P. is same as the n th term of the A.P. find n. Two arithmetic progressions are shown: '9, 7, 5,...' and '15, 12, 9,...'.

Q12 of 202 Page 9

If the n^th term of the A.P.is same as the n^th term of the A.P.find n.

A=9, D=7-9=-2

a=15, d=-3

A_n=a_n

A+(n -1)D=a +(n -1)d

9 – (n -1)2=15 – (n -1)3

(n -1)(3 -2)=6

n -1=6

n=7

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(i)

(ii)

(iii)

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