English

The numbers 3, x, and x + 6 form are in G.P. Find x

Advertisements
Advertisements

Question

The numbers 3, x, and x + 6 form are in G.P. Find x

Sum
Advertisements

Solution

The numbers 3, x, and x + 6 are in G.P.

∴ `"x"/3 = ("x" + 6)/"x"`

∴ x2 = 3x + 18

∴ x2 – 3x – 18 = 0

∴ (x – 6)(x + 3) = 0

∴ x – 6 = 0 or x + 3 = 0

∴ x = 6 or x = – 3

shaalaa.com
  Is there an error in this question or solution?
Chapter 2: Sequences and Series - Exercise 2.1 [Page 28]

APPEARS IN

RELATED QUESTIONS

Find the 20th and nthterms of the G.P. `5/2, 5/4 , 5/8,...`


The 5th, 8th and 11th terms of a G.P. are p, q and s, respectively. Show that q2 = ps.


Find the sum to 20 terms in the geometric progression 0.15, 0.015, 0.0015,…


The sum of first three terms of a G.P. is  `39/10` and their product is 1. Find the common ratio and the terms.


Find a G.P. for which sum of the first two terms is –4 and the fifth term is 4 times the third term.


If the 4th, 10th and 16th terms of a G.P. are x, y and z, respectively. Prove that x, y, z are in G.P.


If the pth, qth and rth terms of a G.P. are a, b and c, respectively. Prove that `a^(q - r) b^(r-p) c^(p-q) = 1`.


In a GP the 3rd term is 24 and the 6th term is 192. Find the 10th term.


If a, b, c, d and p are different real numbers such that:
(a2 + b2 + c2) p2 − 2 (ab + bc + cd) p + (b2 + c2 + d2) ≤ 0, then show that a, b, c and d are in G.P.


The sum of first three terms of a G.P. is 13/12 and their product is − 1. Find the G.P.


Show that the ratio of the sum of first n terms of a G.P. to the sum of terms from (n + 1)th to (2n)th term is \[\frac{1}{r^n}\].


Find the sum of the following serie to infinity:

`2/5 + 3/5^2 +2/5^3 + 3/5^4 + ... ∞.`


Prove that: (91/3 . 91/9 . 91/27 ... ∞) = 3.


Find the rational numbers having the following decimal expansion: 

\[0 . \overline3\]


The sum of first two terms of an infinite G.P. is 5 and each term is three times the sum of the succeeding terms. Find the G.P.


If a, b, c are in G.P., prove that \[\frac{1}{\log_a m}, \frac{1}{\log_b m}, \frac{1}{\log_c m}\] are in A.P.


The sum of three numbers in G.P. is 56. If we subtract 1, 7, 21 from these numbers in that order, we obtain an A.P. Find the numbers.


If a, b, c are in G.P., prove that:

\[a^2 b^2 c^2 \left( \frac{1}{a^3} + \frac{1}{b^3} + \frac{1}{c^3} \right) = a^3 + b^3 + c^3\]


If a, b, c, d are in G.P., prove that:

(a2 + b2), (b2 + c2), (c2 + d2) are in G.P.


If (a − b), (b − c), (c − a) are in G.P., then prove that (a + b + c)2 = 3 (ab + bc + ca)


If pth, qth and rth terms of a G.P. re x, y, z respectively, then write the value of xq − r yr − pzp − q.

 

 

 


If in an infinite G.P., first term is equal to 10 times the sum of all successive terms, then its common ratio is 


If second term of a G.P. is 2 and the sum of its infinite terms is 8, then its first term is


Given that x > 0, the sum \[\sum^\infty_{n = 1} \left( \frac{x}{x + 1} \right)^{n - 1}\] equals 


In a G.P. if the (m + n)th term is p and (m − n)th term is q, then its mth term is 


Check whether the following sequence is G.P. If so, write tn.

`sqrt(5), 1/sqrt(5), 1/(5sqrt(5)), 1/(25sqrt(5))`, ...


For what values of x, the terms `4/3`, x, `4/27` are in G.P.?


If for a sequence, tn = `(5^("n"-3))/(2^("n"-3))`, show that the sequence is a G.P. Find its first term and the common ratio


The value of a house appreciates 5% per year. How much is the house worth after 6 years if its current worth is ₹ 15 Lac. [Given: (1.05)5 = 1.28, (1.05)6 = 1.34]


If the A.M. of two numbers exceeds their G.M. by 2 and their H.M. by `18/5`, find the numbers.


Answer the following:

In a G.P., the fourth term is 48 and the eighth term is 768. Find the tenth term


Answer the following:

If for a G.P. t3 = `1/3`, t6 = `1/81` find r


Answer the following:

If pth, qth and rth terms of a G.P. are x, y, z respectively. Find the value of xq–r .yr–p .zp–q


Answer the following:

Which 2 terms are inserted between 5 and 40 so that the resulting sequence is G.P.


Answer the following:

If p, q, r, s are in G.P., show that (p2 + q2 + r2) (q2 + r2 + s2) = (pq + qr + rs)2   


If pth, qth, and rth terms of an A.P. and G.P. are both a, b and c respectively, show that ab–c . bc – a . ca – b = 1


The third term of a G.P. is 4, the product of the first five terms is ______.


The sum of the infinite series `1 + 5/6 + 12/6^2 + 22/6^3 + 35/6^4 + 51/6^5 + 70/6^6 + ....` is equal to ______.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×