Q9 of 167 Page 20

If , then find the value of n.

Here,

i.e.

(∵a=3;d=2;a’=5;d’=3)

∴n(2+n) =7×5×37

∴n²+2n-1295=0

∴(n-35) (n+37) =0

∴ n=35 or n=-37 which is not possible as n is non negative.

So,n=35

Write the sum of first n even natural numbers.

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If mth term of an A.P. is n and nth term is m, then write its pth term.

If the sum of n terms of two A.P.’s are in the ratio (3n + 2) : (2n + 3), find the ratio of their 12^th terms.