Home
Class 11
MATHS
If the middle term in the binomial expan...

If the middle term in the binomial expansion of `(1/x+xsinx)^(10)` is equal to `(63)/8,` find the value of `xdot`

A

`2n pi + (pi)/(6)`

B

`n pi + (pi)/(6)`

C

`n pi + (-1)^(n) (pi)/(6)`

D

`n pi + (-1)^(n) (pi)/(3)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem step by step, we need to find the middle term in the binomial expansion of \((\frac{1}{x} + x \sin x)^{10}\) and set it equal to \(\frac{63}{8}\). ### Step 1: Identify the middle term In a binomial expansion of the form \((a + b)^n\), the middle term is given by the formula: \[ T_{r+1} = \binom{n}{r} a^{n-r} b^r \] For \(n = 10\), the middle term will be the \(T_{6}\) term (since \(n/2 + 1 = 5 + 1 = 6\)). ### Step 2: Set up the expression for the middle term Here, \(a = \frac{1}{x}\) and \(b = x \sin x\). Thus, we can express the middle term as: \[ T_6 = \binom{10}{5} \left(\frac{1}{x}\right)^{10-5} (x \sin x)^5 \] ### Step 3: Simplify the middle term Substituting the values we have: \[ T_6 = \binom{10}{5} \left(\frac{1}{x}\right)^{5} (x \sin x)^5 \] This simplifies to: \[ T_6 = \binom{10}{5} \frac{(x \sin x)^5}{x^5} = \binom{10}{5} (\sin x)^5 \] ### Step 4: Calculate \(\binom{10}{5}\) \[ \binom{10}{5} = \frac{10!}{5!5!} = \frac{10 \times 9 \times 8 \times 7 \times 6}{5 \times 4 \times 3 \times 2 \times 1} = 252 \] Thus, we have: \[ T_6 = 252 (\sin x)^5 \] ### Step 5: Set the middle term equal to \(\frac{63}{8}\) We set the equation: \[ 252 (\sin x)^5 = \frac{63}{8} \] ### Step 6: Solve for \((\sin x)^5\) Dividing both sides by 252: \[ (\sin x)^5 = \frac{63}{8 \times 252} \] Calculating \(8 \times 252 = 2016\): \[ (\sin x)^5 = \frac{63}{2016} \] Simplifying \(\frac{63}{2016}\): \[ (\sin x)^5 = \frac{1}{32} \] ### Step 7: Solve for \(\sin x\) Taking the fifth root: \[ \sin x = \left(\frac{1}{32}\right)^{\frac{1}{5}} = \frac{1}{2} \] ### Step 8: Find the value of \(x\) The general solution for \(\sin x = \frac{1}{2}\) is: \[ x = n\pi + (-1)^n \frac{\pi}{6}, \quad n \in \mathbb{Z} \] ### Conclusion Thus, the values of \(x\) can be expressed as: \[ x = n\pi + (-1)^n \frac{\pi}{6}, \quad n \in \mathbb{Z} \]

To solve the problem step by step, we need to find the middle term in the binomial expansion of \((\frac{1}{x} + x \sin x)^{10}\) and set it equal to \(\frac{63}{8}\). ### Step 1: Identify the middle term In a binomial expansion of the form \((a + b)^n\), the middle term is given by the formula: \[ T_{r+1} = \binom{n}{r} a^{n-r} b^r \] For \(n = 10\), the middle term will be the \(T_{6}\) term (since \(n/2 + 1 = 5 + 1 = 6\)). ...
Promotional Banner

Topper's Solved these Questions

  • BINOMIAL THEOREM

    NCERT EXEMPLAR ENGLISH|Exercise True/False|7 Videos
  • BINOMIAL THEOREM

    NCERT EXEMPLAR ENGLISH|Exercise Long Answer type question|6 Videos
  • COMPLEX NUMBERS AND QUADRATIC EQUATIONS

    NCERT EXEMPLAR ENGLISH|Exercise OBJECTIVE TYPE QUESTIONS|16 Videos

Similar Questions

Explore conceptually related problems

If the middle term in the binomial expansion of ((1)/(x) + x sin x )^(10) is ( 63)/( 8) , then the value of 6sin^(2) x +sin x -2 is

If the middle term in the expansion of ((1)/(x)+x sinx)^(10) is equal to 7(7)/(8) , then the principal value of x is:

Find the middle term in the expansion of (2x^2-1/x)^7

Find the middle term in the expansion of (2x^2-1/x)^7

If the middle term in the expansion of (1/x+xsinx)^(10) is equal to 7 7/8 , then the value of x is (i) 2npi+(pi)/6 (ii) npi+(pi)/6 (iii) npi+(-1)^(n)(pi)/6 (iv) npi+(-1)^(n)(pi)/3

Find the middle term in the expansion of : (1-2x+x^2)^n

Find the middle term in the expansion of (x- 1/(2x))^12

Find the middle term in the expansion of (x/y-y/x)^7

Find the 10th term in the binomial expansion of (2x^2+1/x)^(12)dot

Find the 10th term in the binomial expansion of (2x^2+1/x)^(12)dot