Consider the following expression and find the value of ‘x’: \[8{{x}^{\dfrac{3}{2n}}}-8{{x}^{-\dfrac{3}{2n}}}=63\]
This question has multiple correct options.
A. \[{{2}^{2n}}\]
B. \[{{2}^{\dfrac{1}{2n}}}\]
C. \[{{2}^{3n}}\]
D. \[{{2}^{\dfrac{1}{3n}}}\]
Answer
654.6k+ views
Hint: First consider the \[{{x}^{\dfrac{3}{2n}}}=y\]by replacing this value by y then we will get quadratic equation in y. solve the quadratic equation in y then we will get values of y and again replace y by corresponding value in x then we will get the value of x.
Complete step by step answer:
Given that \[8{{x}^{\dfrac{3}{2n}}}-8{{x}^{-\dfrac{3}{2n}}}=63\]
For this problem we have to find the value of x
Let us consider \[{{x}^{\dfrac{3}{2n}}}=y\]
Replacing that value by x then we will get the equation as follows
\[8y-8{{y}^{-1}}=63\]
\[8y-\dfrac{8}{y}=63\]
\[8{{y}^{2}}-8=63y\]
\[8{{y}^{2}}-63y-8=0\]. . . . . . . . . . . (1)
Now solve the above equation quadratic equation then we will get values of y as follows
\[8{{y}^{2}}-64y+y-8=0\]
\[8y\left( y-8 \right)+1\left( y-8 \right)=0\]
\[\left( y-8 \right)\left( 8y+1 \right)=0\]
\[y=8,y=-\dfrac{1}{8}\]
So the obtained values of y is \[y=8,y=-\dfrac{1}{8}\]. . . . . . . . . . (2)
First we have considered that \[{{x}^{\dfrac{3}{2n}}}=y\]
Let us take \[y=8\]
\[{{x}^{\dfrac{3}{2n}}}=8\]
8 can be written 2 to the power of 3
\[{{x}^{\dfrac{3}{2n}}}={{2}^{3}}\]
\[x={{({{2}^{3}})}^{\dfrac{2n}{3}}}\]
\[x={{2}^{2n}}\]. . . . . . . . . . . (3)
So the obtained value of x for y=8 is \[x={{2}^{2n}}\]
Let us take \[y=-\dfrac{1}{8}\]
\[\dfrac{1}{8}\]can be 2 to the power of -3
\[{{x}^{\dfrac{3}{2n}}}=-\dfrac{1}{8}\]
\[{{x}^{\dfrac{3}{2n}}}=-{{2}^{-3}}\]
\[x={{(-{{2}^{-3}})}^{\dfrac{2n}{3}}}\]
\[x={{\left( -2 \right)}^{-2n}}\]
\[x={{\left( 2 \right)}^{-2n}}\]
\[x={{\left( 2 \right)}^{\dfrac{1}{2n}}}\]. . . . . . . . . . . (4)
So the obtained value of x for \[y=-\dfrac{1}{8}\]is \[x={{\left( 2 \right)}^{\dfrac{1}{2n}}}\]
So the correct option is option (A), (B).
Note:
In this problem we will get quadratic in y so we can get two values of y , we have considered a corresponding value in x by y so we also get two of values of x. we used factorization method to solve quadratic equation in y we can get the two values of y either by factorization method or using formula.
Complete step by step answer:
Given that \[8{{x}^{\dfrac{3}{2n}}}-8{{x}^{-\dfrac{3}{2n}}}=63\]
For this problem we have to find the value of x
Let us consider \[{{x}^{\dfrac{3}{2n}}}=y\]
Replacing that value by x then we will get the equation as follows
\[8y-8{{y}^{-1}}=63\]
\[8y-\dfrac{8}{y}=63\]
\[8{{y}^{2}}-8=63y\]
\[8{{y}^{2}}-63y-8=0\]. . . . . . . . . . . (1)
Now solve the above equation quadratic equation then we will get values of y as follows
\[8{{y}^{2}}-64y+y-8=0\]
\[8y\left( y-8 \right)+1\left( y-8 \right)=0\]
\[\left( y-8 \right)\left( 8y+1 \right)=0\]
\[y=8,y=-\dfrac{1}{8}\]
So the obtained values of y is \[y=8,y=-\dfrac{1}{8}\]. . . . . . . . . . (2)
First we have considered that \[{{x}^{\dfrac{3}{2n}}}=y\]
Let us take \[y=8\]
\[{{x}^{\dfrac{3}{2n}}}=8\]
8 can be written 2 to the power of 3
\[{{x}^{\dfrac{3}{2n}}}={{2}^{3}}\]
\[x={{({{2}^{3}})}^{\dfrac{2n}{3}}}\]
\[x={{2}^{2n}}\]. . . . . . . . . . . (3)
So the obtained value of x for y=8 is \[x={{2}^{2n}}\]
Let us take \[y=-\dfrac{1}{8}\]
\[\dfrac{1}{8}\]can be 2 to the power of -3
\[{{x}^{\dfrac{3}{2n}}}=-\dfrac{1}{8}\]
\[{{x}^{\dfrac{3}{2n}}}=-{{2}^{-3}}\]
\[x={{(-{{2}^{-3}})}^{\dfrac{2n}{3}}}\]
\[x={{\left( -2 \right)}^{-2n}}\]
\[x={{\left( 2 \right)}^{-2n}}\]
\[x={{\left( 2 \right)}^{\dfrac{1}{2n}}}\]. . . . . . . . . . . (4)
So the obtained value of x for \[y=-\dfrac{1}{8}\]is \[x={{\left( 2 \right)}^{\dfrac{1}{2n}}}\]
So the correct option is option (A), (B).
Note:
In this problem we will get quadratic in y so we can get two values of y , we have considered a corresponding value in x by y so we also get two of values of x. we used factorization method to solve quadratic equation in y we can get the two values of y either by factorization method or using formula.
Recently Updated Pages
Write structures of the following compounds i 2 Chloro3methylpentane class 11 chemistry CBSE

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

A Paragraph on Pollution in about 100-150 Words

XIX+XXX A 49 B 51 C 55 D 44 class 5 maths CBSE

If x a + bt + ct2 where x is in meters and t is in class 11 physics CBSE

Trending doubts
One Metric ton is equal to kg A 10000 B 1000 C 100 class 11 physics CBSE

Find the value of the expression given below sin 30circ class 11 maths CBSE

What do you mean by retardation What is its SI uni class 11 physics CBSE

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

10 examples of friction in our daily life

Difference between physical and chemical change class 11 chemistry CBSE

