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The first two terms of a G.P. are 125 an...

The first two terms of a G.P. are 125 and 25 respectively. Find the `5^(th)` and the `6^(th)` terms of the G.P.

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To solve the problem, we need to find the 5th and 6th terms of a geometric progression (G.P.) where the first two terms are given as 125 and 25. ### Step 1: Identify the first term and the second term Let the first term \( t_1 = 125 \) and the second term \( t_2 = 25 \). ### Step 2: Calculate the common ratio The common ratio \( r \) of a G.P. can be found using the formula: \[ r = \frac{t_2}{t_1} \] Substituting the values: \[ r = \frac{25}{125} = \frac{1}{5} \] ### Step 3: Use the formula for the nth term of a G.P. The nth term of a G.P. is given by the formula: \[ t_n = a \cdot r^{n-1} \] where \( a \) is the first term and \( r \) is the common ratio. ### Step 4: Find the 5th term To find the 5th term \( t_5 \): \[ t_5 = a \cdot r^{5-1} = 125 \cdot \left(\frac{1}{5}\right)^4 \] Calculating \( \left(\frac{1}{5}\right)^4 \): \[ \left(\frac{1}{5}\right)^4 = \frac{1}{625} \] Now, substituting back: \[ t_5 = 125 \cdot \frac{1}{625} = \frac{125}{625} = \frac{1}{5} \] ### Step 5: Find the 6th term To find the 6th term \( t_6 \): \[ t_6 = a \cdot r^{6-1} = 125 \cdot \left(\frac{1}{5}\right)^5 \] Calculating \( \left(\frac{1}{5}\right)^5 \): \[ \left(\frac{1}{5}\right)^5 = \frac{1}{3125} \] Now, substituting back: \[ t_6 = 125 \cdot \frac{1}{3125} = \frac{125}{3125} = \frac{1}{25} \] ### Final Answer Thus, the 5th term \( t_5 \) is \( \frac{1}{5} \) and the 6th term \( t_6 \) is \( \frac{1}{25} \). ---
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ICSE-GEOMETRIC PROGRESSION -Exercise 11(D)
  1. How many terms of the geometric progression 1+4+16+64+ . . . . .. . . ...

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  2. If the first term of a G.P is 27 and 8th term is 1/81, then the sum of...

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  3. A boy spends Rs. 10 on first day, Rs. 20 on second day, Rs. 40 on thir...

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  4. The 4^(th) and the 7^(th) terms of a G.P. are (1)/(27) and (1)/(729) r...

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  5. A geometric progression has common ratio = 3 and last term = 486. If t...

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  6. Find the sum of G.P. : 3,6,12, . . . . . . . . ., 1536.

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  7. How many terms of the series 2+6+18+ . . . . . . . . . . . Must be tak...

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  8. In a G.P., the ratio between the sum of first three terms and that of ...

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  9. How many terms of the G.P. (2)/(9),-(1)/(3),(1)/(2), . . . . . . . ....

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  10. If the sum of 1+2+2^(2)+ . . . . . . . . . .+2^(n-1) is 255, find the ...

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  11. Find the geometric mean between : (4)/(9) and (9)/(4)

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  12. Find the geometric mean between : 14 and (7)/(32)

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  13. Find the geometric mean between : 2a and 8a^(3)

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  14. The sum of three numbers in G.P. is (39)/(10) and their product is 1. ...

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  15. The first term of a G.P. is -3 and the square of the second term is eq...

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  16. Find the 5^(th) term of the G.P. (5)/(2),1. . . . . . . . .

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  17. The first two terms of a G.P. are 125 and 25 respectively. Find the 5^...

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  18. Find the sum of the sequence -(1)/(3),1,-3,9, . . . . . . . Upto 8 te...

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  19. The first term of a G.P. in 27. If the 8^(th) term be (1)/(81), what w...

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  20. Find a G.P. for which the sum of first two terms is -4 and the fifth i...

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