The number which should be added to the numbers 2, 14, 62 so that the resulting numbers may be in G.P., is
A.1
B.2
C.3
D.4
Answer
577.8k+ views
Hint: Here in this question, we have to find the number which should be added to the given number to become a geometric progression (G.P). For this, first we need to consider the unknown number be \[x\] and next consider the formula of the geometric mean of GP i.e., \[{b^2} = ac\] . To further simplify by using an algebraic identity and arithmetic operations to get the required solution.
Complete step-by-step answer:
Geometric Progression (G.P.) is a type of sequence where each succeeding term of the sequence is produced by multiplying each preceding term by a fixed number, which is called a common ratio.
In general, the geometric progression is represented by:
\[a\] , \[ar\] , \[a{r^2}\] , \[a{r^3}\] , and so on.
Where ‘ \[a\] ’ is the first term and ‘ \[r\] ’ is the common ratio.
If a, b and c are three quantities in GP, then b is the geometric mean of a and c. Mathematically this can be written as: \[{b^2} = ac\]
Consider the given question:
Let us take \[x\] be any number added to 2, 14, 62.
So, that the resulting numbers may be in GP is
\[2 + x\] , \[14 + x\] , \[62 + x\] -----(1)
The geometric mean of the above G.P is
\[ \Rightarrow {\left( {14 + x} \right)^2} = \left( {2 + x} \right)\left( {62 + x} \right)\]
Apply a algebraic identity \[{\left( {a + b} \right)^2} = {a^2} + {b^2} + 2ab\] in LHS and multiply the binomials in RHS, then we have
\[ \Rightarrow {14^2} + {x^2} + 2\left( {14} \right)\left( x \right) = 124 + 2x + 62x + {x^2}\]
\[ \Rightarrow 196 + {x^2} + 28x = 124 + 64x + {x^2}\]
Take variable \[x\] and its coefficient term to the LHS and constant term to the RHS, then
\[ \Rightarrow {x^2} + 28x - {x^2} - 64x = 124 - 196\]
\[ \Rightarrow - 36x = - 72\]
Divide both side by \[ - 36\] , then we get
\[ \Rightarrow x = \dfrac{{ - 72}}{{ - 36}}\]
\[\therefore x = 2\]
The required resultant G.P is:
\[ \Rightarrow 2 + 2\] , \[14 + 2\] , \[62 + 2\]
\[\therefore 4\] , \[16\] , \[64\]
Because, here the common ratio \[r = 4\] is multiplied with two successive terms.
Hence, the required number is \[x = 2\]
Therefore, option (B) is the correct answer.
So, the correct answer is “Option B”.
Note: We must know about the geometric progression arrangement and it is based on the first term and common ratio. The common ratio \[r\] is multiplied uniformly with successive terms and If three quantities are in GP, then the middle one is called the geometric mean of the other two terms.
Complete step-by-step answer:
Geometric Progression (G.P.) is a type of sequence where each succeeding term of the sequence is produced by multiplying each preceding term by a fixed number, which is called a common ratio.
In general, the geometric progression is represented by:
\[a\] , \[ar\] , \[a{r^2}\] , \[a{r^3}\] , and so on.
Where ‘ \[a\] ’ is the first term and ‘ \[r\] ’ is the common ratio.
If a, b and c are three quantities in GP, then b is the geometric mean of a and c. Mathematically this can be written as: \[{b^2} = ac\]
Consider the given question:
Let us take \[x\] be any number added to 2, 14, 62.
So, that the resulting numbers may be in GP is
\[2 + x\] , \[14 + x\] , \[62 + x\] -----(1)
The geometric mean of the above G.P is
\[ \Rightarrow {\left( {14 + x} \right)^2} = \left( {2 + x} \right)\left( {62 + x} \right)\]
Apply a algebraic identity \[{\left( {a + b} \right)^2} = {a^2} + {b^2} + 2ab\] in LHS and multiply the binomials in RHS, then we have
\[ \Rightarrow {14^2} + {x^2} + 2\left( {14} \right)\left( x \right) = 124 + 2x + 62x + {x^2}\]
\[ \Rightarrow 196 + {x^2} + 28x = 124 + 64x + {x^2}\]
Take variable \[x\] and its coefficient term to the LHS and constant term to the RHS, then
\[ \Rightarrow {x^2} + 28x - {x^2} - 64x = 124 - 196\]
\[ \Rightarrow - 36x = - 72\]
Divide both side by \[ - 36\] , then we get
\[ \Rightarrow x = \dfrac{{ - 72}}{{ - 36}}\]
\[\therefore x = 2\]
The required resultant G.P is:
\[ \Rightarrow 2 + 2\] , \[14 + 2\] , \[62 + 2\]
\[\therefore 4\] , \[16\] , \[64\]
Because, here the common ratio \[r = 4\] is multiplied with two successive terms.
Hence, the required number is \[x = 2\]
Therefore, option (B) is the correct answer.
So, the correct answer is “Option B”.
Note: We must know about the geometric progression arrangement and it is based on the first term and common ratio. The common ratio \[r\] is multiplied uniformly with successive terms and If three quantities are in GP, then the middle one is called the geometric mean of the other two terms.
Recently Updated Pages
What is BLO What is the full form of BLO class 8 social science CBSE

Explain the Treaty of Vienna of 1815 class 10 social science CBSE

10 examples of friction in our daily life

Draw a diagram of nephron and explain its structur class 11 biology CBSE

Write structures of the following compounds i 2 Chloro3methylpentane class 11 chemistry CBSE

A Paragraph on Pollution in about 100-150 Words

Trending doubts
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE

Difference Between Plant Cell and Animal Cell

Name 10 Living and Non living things class 9 biology CBSE

What is the full form of pH?

What is pollution? How many types of pollution? Define it

On an outline map of India show its neighbouring c class 9 social science CBSE

