Question Bank - Mathematics

Here's the question bank on all the mathematics topics.

If a, b, c are in GP where a > 0, b > 0, c > 0, then which of the following are correct?1. a2, b2, c2 are in GP2. \(\frac{1}{a}, \frac{1}{b}, \frac{1}{c}\) are in GP3. \(\sqrt {a}, \sqrt{b}, \sqrt{c} \) are in GPSelect the correct answer using the code given below :

A.
1 and 2 only
B.
2 and 3 only
C.
1 and 3 only
D.
1, 2 and 3

Solution:

Concept:1). The general form of terms of a GP is a, ar, ar2, ar3, and so on. Here, a is the first term and r is the common ratio. The nth term of a GP is Tn = arn-1 Common ratio = r = Tn/ Tn-12). If a, b and c are three quantities in GP, then and b is the geometric mean of a and c. This can be written as b2 = ac or b =?acCalculation:Given:a, b, c are in GP where a > 0, b > 0, c > 0Statement I: a2, b2, c2 are in GPAs b is G.M. of a and c, b2 = acSquaring on both sides ? b4 = a2c2? (b2)2 = (a2)(c2) ? b2 is G.M. of a2 and c2a2, b2, and c2 are in GPStatement II: \(\frac{1}{a}, \frac{1}{b}, \frac{1}{c}\) are in GPLet the common ratio be r.? b = ar? c = br = ar2Now, \(\displaystyle \frac{\frac{1}{b}}{\frac{1}{a}}=\frac{a}{b}=\frac{a}{ar}=\frac{1}{r}\)? \(\displaystyle \frac{\frac{1}{c}}{\frac{1}{b}}=\frac{b}{c}=\frac{ar}{ar^2}=\frac{1}{r}\)1/a,1/b,1/c are in G.P.Statement III: \(? {a}, ?{b}, ?{c} \) are in GPAs b is G.M. of a and c, ?\({b} = ?{ac}\)?Taking square roots on both sides ? \( ?{b} = ?{?{a} ?{c}} \)? ?b is GM of ?a and ?c \(? {a}, ?{b}, \ and\ ?{c} \) are in GP? Statement I, II, and III are correct.

For more questions,

Click Here

Download Gyanm App

free current affairs for competitive exams

Scan QR code to download our App for
more exam-oriented questions

free current affairs for competitive exams

OR
To get link to download app

Thank you! Your submission has been received. You will get the pdf soon. Call us if you have any question: 9117343434
Oops! Something went wrong while submitting the form.