Question 14

Let S be the sum, P the product and R the sum of reciprocals of *n* terms in a G.P. Prove that P^{2}R^{n} = S^{n}

Answer

Let the G.P. be *a*, *ar*, *ar*^{2}, *ar*^{3}, … *ar*^{n – 1}…

According to the given information,

Hence P^{2} R^{n}= S_{n}

- Q:-
Find the sum of integers from 1 to 100 that are divisible by 2 or 5.

- Q:-
If the sum of three numbers in A.P., is 24 and their product is 440, find the numbers.

- Q:-
A wheel makes 360 revolutions in one minute. Through how many radians does it turn in one second?

- Q:- Find the sum of all natural numbers lying between 100 and 1000, which are multiples of 5.
- Q:-
The sum of the first four terms of an A.P. is 56. The sum of the last four terms is 112. If its first term is 11, then find the number of terms.

- Q:-
How many terms of G.P. 3, 3

^{2}, 3^{3}, … are needed to give the sum 120? - Q:-
Find the sum of all numbers between 200 and 400 which are divisible by 7.

- Q:- Write the following sets in roster form:

(i) A = {x: x is an integer and - 3 < x < 7}.

(ii) B = {x: x is a natural number less than 6}.

(iii) C = {x: x is a two-digit natural number such that the sum of its digits is 8}

(iv) D = {x: x is a prime number which is divisor of 60}.

(v) E = The set of all letters in the word TRIGONOMETRY.

(vi) F = The set of all letters in the word BETTER. - Q:-
Insert five numbers between 8 and 26 such that the resulting sequence is an A.P.

- Q:-
Find the sum of all two digit numbers which when divided by 4, yields 1 as remainder.

- Q:-
How many terms of G.P. 3, 3

^{2}, 3^{3}, … are needed to give the sum 120? - Q:-
Describe the sample space for the indicated experiment: A coin is tossed and then a die is rolled only in case a head is shown on the coin.

- Q:-
Find the sum to

*n*terms of the series whose*n*th term is given by*n*(*n*+ 1) (*n*+ 4). - Q:- Find the sum to n terms of the A.P., whose kth term is 5k + 1.
- Q:-
The sum of first three terms of a G.P. is 16 and the sum of the next three terms is 128. Determine the first term, the common ratio and the sum to

*n*terms of the G.P. - Q:-
One die of red colour, one of white colour and one of blue colour are placed in a bag. One die is selected at random and rolled, its colour and the number on its uppermost face is noted. Describe the sample space.

- Q:-
A die is thrown repeatedly until a six comes up. What is the sample space for this experiment?

- Q:-
Between 1 and 31,

*m*numbers have been inserted in such a way that the resulting sequence is an A.P. and the ratio of 7th and (*m*– 1)thnumbers is 5:9. Find the value of*m*. - Q:-
Find the sum of all numbers between 200 and 400 which are divisible by 7.

- Q:-
If the first and the

*n*th term of a G.P. are*a*ad*b*, respectively, and if*P*is the product of*n*terms, prove that*P*^{2}= (*ab*)^{n}.

Kunal
2019-02-01 08:51:31

Thanx....ð

Adi
2018-12-24 08:31:22

Ty

Anjali
2018-10-18 09:32:23

Thanks for the solution

Nitesh
2018-09-11 12:40:59

Not satisfied

Vishu
2018-08-04 15:47:39

Nice

Sweety
2018-04-06 13:01:43

P^2 = (S/R)^n

frankestine
2017-03-23 21:33:23

the answer is not easy to understand

Evam Spy
2017-02-21 00:53:01

The color of the page is very uncomfortable to the eyes

Dibyashree Bagchi
2017-01-17 12:49:58

Thank you so much...

Sudhanshu
2016-12-15 04:36:06

I have better solution than yours

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