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If f is a function satisfying f (x +y) = f(x) f(y) for all `x, y in N` such that `f(1) = 3 and sum _(x=1)^nf(x)=120` , find the value of n.

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The correct Answer is:
n=4
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KUMAR PRAKASHAN-SEQUENCE AND SERIES-Miscellaneous Exercise
  1. Find the sum of integers from 1 to 100 that are divisible by 2 or 5.

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  2. Find the sum of all two digit numbers which when divided by 4, yields ...

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  3. If f is a function satisfying f (x +y) = f(x) f(y) for all x, y in N ...

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  4. The sum of some terms of G.P. is 315 whose first term and the common r...

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  5. The first term of a G.P. is 1. The sum of the third term and fifth ter...

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  6. The sum of three numbers in G.P. is 56. If we subtract 1, 7, 21 from t...

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  7. A G.P. consists of an even number of terms. If the sum of all the term...

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  8. The sum of the first four terms of an A.P. is 56. The sum of the last ...

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  9. If (a+bx)/(a-bx)=(b-cx)/(b-cx)=(c+dx)/(c-dx)( x ne 0) then show that ...

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  10. Let S be the sum, P the product and R the sum of reciprocals of n term...

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  11. The p^(th), q^(th) and r^(th) terms of an A.P. are a, b, c, respectiv...

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  12. If a(1/b+1/c),b(1/c+1/a),c(1/a+1/b) are in A.P., prove that a,b,c are...

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  13. If a, b, c, d are in G.P, prove that (a^n + b^n), (b^n + c^n), (c^n +...

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  14. If a and b are the roots of x^2 – 3x + p = 0 and c, d are roots of x^...

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  15. The ratio of the A.M. and G.M. of two positive numbers a and b, is m :...

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  16. If a, b, c are in A.P., b, c, d are in G.P. and 1/c,1/d,1/e are in A.P...

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  17. Find the sum of the following series up to n terms: (i) 5+55+555+......

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  18. Find the sum of the following series up to n terms: (i) 5+55+555+......

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  19. Find the 20^(th) term of the series 2 xx 4 + 4 xx 6 + 6 xx 8 + ... + ...

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  20. Find the sum of the first n terms of the series: 3+ 7 +13 +21 +31 +......

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