Tag: maths

Questions Related to maths

Which of the following is a general form of geometric sequence?

  1. {$2, 4, 6, 8, 10$}

  2. {$-1, 2, 4, 8, -2$}

  3. {$2, -2, 2, -2, 2$}

  4. {$3, 13, 23, 33, 43$}


Correct Option: C
Explanation:

{$2, -2, 2, -2, 2$} is a general form of geometric sequence.

For a G.P, the ratio must be equal throughout.
Here the common ratio is $-1$.

The common ratio is calculated in

  1. A.P.

  2. G.P.

  3. H.P.

  4. I.P.


Correct Option: B
Explanation:

The common ratio is calculated in G.P.
For example: $2,4,8,16,....$

Here the common ratio is $2$.

The series $a, ar, ar^2, ar^3, ar^4....$ is an

  1. finite geometric progression

  2. finite harmonic progression

  3. infinite geometric progression

  4. finite arithmetic progression


Correct Option: C
Explanation:

$a, ar, ar^2, ar^3, ar^4....$ is an infinite geometric progression.

Here common ratio is $r$.
This can be found out as $\dfrac {ar}{a}=r, \dfrac {ar^2}{ar}=r$ and so on.
Thus the given series is in G.P.

The general form of GP $a, ar, ar^2, ar^3, ar^4$ is a

  1. finite geometric progression

  2. finite harmonic progression

  3. infinite geometric progression

  4. finite arithmetic progression


Correct Option: A
Explanation:

Given sequence is $a,ar,ar^2, ar^3, ar^4$.

It is the general form of a finite geometric progression as the series stops at some point of finite terms.

$1 + 0.5 + 0.25 + 0.125....$ is an example of

  1. finite geometric progression

  2. infinite geometric series

  3. finite geometric sequence

  4. infinite geometric progression


Correct Option: D
Explanation:

$1 + 0.5 + 0.25 + 0.125....$ is an example of infinite geometric progression.
Here the common ratio is $0.5$.
An infinite geometric series is the sum of an infinite geometric progression.

How will you identify the sequence is an infinite geometric progression?

  1. An geometric sequence containing finite number of terms

  2. An geometric sequence containing infinite number of terms

  3. An arithmetic sequence containing infinite number of terms

  4. An arithmetic sequence containing finite number of terms


Correct Option: B
Explanation:

An geometric sequence containing infinite number of terms. It has a common ratio which is same throughout.
Example: $1 + 0.5 + 0.25 + 0.125....$ is an infinite geometric sequence.
Here the common ratio is $0.5$.

How would you find the sequence is finite geometric sequence?

  1. An arithmetic sequence containing finite number of terms

  2. A geometric sequence containing finite number of terms

  3. An arithmetic sequence containing infinite number of terms

  4. A geometric sequence containing infinite number of terms


Correct Option: B
Explanation:

If a sequence is a finite geometric sequence, then :

It will have the finite number of terms.
it will be a geometric sequence i.e. its ratio will be constant throughout.
Option B is the correct answer.

Identify the finite geometric progression.

  1. $3, 6, 12, 24...$

  2. $81, 27, 9, 3..$

  3. $10 - 5 + 2.5 - 1.25.....$

  4. $1 + 0.5 + 0.25 + 0.125$


Correct Option: D
Explanation:

$1 + 0.5 + 0.25 + 0.125 $$ is a finite geometric progression.
Here the common ratio is $0.5$.
An finite geometric series is the sum of an finite geometric sequence.

Identify the correct sequence represents a infinite geometric sequence.

  1. $3, 6, 12, 24, 48$

  2. $1 + 2 + 4 + 8 +....$

  3. $1, -1, 1, -1, 1$

  4. $1, 3, 4, 5, 6....$


Correct Option: B
Explanation:

An infinite geometric series is the sum of an infinite geometric sequence.
So, $1 + 2 + 4 + 8 +....$ is an infinite geometric sequence.
Here the common ratio is $2$ and it is never ending.

If $\dfrac{a-b}{b-c}=\dfrac{a}{b}$, then $a, b, c $ are in

  1. GP

  2. HP

  3. AP

  4. SP


Correct Option: A
Explanation:

Given:

$\dfrac{a-b}{b-c}=\dfrac{a}{b}$
$\Rightarrow ab-b^{2}=ab-ac$
$\therefore b^{2}=acĀ  \rightarrow G.P.$
$(Ans \to A)$