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In the binomial expansion of ( root(3) (...

In the binomial expansion of `( root(3) (4) + sqrt(2) )^5` find the term which does not contain Irrational expression.

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To solve the problem, we need to find the term in the binomial expansion of \( \left( \sqrt[3]{4} + \sqrt{2} \right)^5 \) that does not contain any irrational expression. ### Step-by-Step Solution: 1. **Identify the General Term**: The general term \( T_{r+1} \) in the binomial expansion of \( (x + y)^n \) is given by: \[ T_{r+1} = \binom{n}{r} x^{n-r} y^r \] Here, \( n = 5 \), \( x = \sqrt[3]{4} \), and \( y = \sqrt{2} \). 2. **Write the General Term for Our Expression**: For our case, the general term becomes: \[ T_{r+1} = \binom{5}{r} \left( \sqrt[3]{4} \right)^{5-r} \left( \sqrt{2} \right)^r \] 3. **Simplify the General Term**: We can rewrite \( \sqrt[3]{4} \) as \( 4^{1/3} \) and \( \sqrt{2} \) as \( 2^{1/2} \): \[ T_{r+1} = \binom{5}{r} \cdot 4^{(5-r)/3} \cdot 2^{r/2} \] 4. **Determine Conditions for Rationality**: For the term to be rational, both \( 4^{(5-r)/3} \) and \( 2^{r/2} \) must be rational numbers. This requires: - \( \frac{5-r}{3} \) must be an integer (i.e., \( 5 - r \) must be a multiple of 3). - \( \frac{r}{2} \) must also be an integer (i.e., \( r \) must be even). 5. **Find Possible Values of \( r \)**: Since \( r \) must be even, let \( r = 2k \) where \( k \) is an integer. The possible values of \( r \) from 0 to 5 are 0, 2, and 4. - For \( r = 0 \): \( 5 - r = 5 \) (not a multiple of 3) - For \( r = 2 \): \( 5 - r = 3 \) (is a multiple of 3) - For \( r = 4 \): \( 5 - r = 1 \) (not a multiple of 3) Thus, the only valid value for \( r \) is 2. 6. **Calculate the Specific Term**: Substitute \( r = 2 \) into the general term: \[ T_{3} = \binom{5}{2} \left( \sqrt[3]{4} \right)^{5-2} \left( \sqrt{2} \right)^2 \] \[ = \binom{5}{2} \left( \sqrt[3]{4} \right)^{3} \cdot 2 \] \[ = \binom{5}{2} \cdot 4 \cdot 2 \] \[ = 10 \cdot 4 \cdot 2 = 80 \] ### Conclusion: The term in the binomial expansion of \( \left( \sqrt[3]{4} + \sqrt{2} \right)^5 \) that does not contain any irrational expression is \( 80 \).
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ICSE-BINOMIAL THEOREM-EXERCISE 13 (a)
  1. Write out the expansions of the following: (3x-y)^(4)

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  2. Write out the expansions of the following: (3+2x^(2) )^(4)

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  3. Write out the expansions of the following: (c ) (x- (y)/(2) )^(4)

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  4. Write out the expansion of the following: (2x + (y)/(2) )^(5)

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  5. Write out the expansions of the following: (e ) (1+2x)^(7)

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  6. Write out the expansions of the following: (f) ((2)/(x) - (x)/(2) )^...

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  7. Using binomial theorem, expand [ ( x+y)^(5) + (x-y)^(5) ] and hence fi...

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  8. Expand (2+ x)^(5) - (2- x)^(5) in ascending powers of x and simplify y...

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  9. Evaluate the following: (i) (2 + sqrt(5) )^(5) + (2 - sqrt(5) )^(5) ...

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  10. If the first three terms in the expansion of (1 + ax)^(n) in ascending...

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  11. Find the first three terms in the expansion of [ 2+ x ( 3+ 4x)]^(5) in...

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  12. Expand (1+ 2 x + 3x^(2) )^(n) in a series of ascending powers of x up ...

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  13. Write down the expansion by the binomial theorem of (3x - (y)/(2) )^(4...

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  14. Using binomial theorem, evaluate : (999)^(3).

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  15. Write down in terms of x and n, the term containing x^3 in the expans...

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  16. (i) Obtain the binomial expansion of (2- sqrt(3) )^(6) in the form a+b...

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  17. Find the coefficient of x^5 in the expansion of (1 + 2x)^6 (1-x)^7.

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  18. If the coefficients of second, third and fourth terms in the expansion...

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  19. Let n be a positive integer. If the coefficients of 2nd, 3rd, 4th term...

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  20. In the binomial expansion of ( root(3) (4) + sqrt(2) )^5 find the term...

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