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Evaluate the following: (i) (2 + sqrt(...

Evaluate the following:
(i) `(2 + sqrt(5) )^(5) + (2 - sqrt(5) )^(5)`
(ii) `( sqrt(3) + 1)^(5) - ( sqrt(3) - 1)^(5) `
Hence, show in (ii), without using tables, that the value of `( sqrt(3) + 1)^(5)` lies between 152 and 153.

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To solve the given problems step by step, we will use the Binomial Theorem and some algebraic manipulations. ### (i) Evaluate \( (2 + \sqrt{5})^5 + (2 - \sqrt{5})^5 \) 1. **Identify the binomial terms**: Let \( x = 2 \) and \( y = \sqrt{5} \). We will use the Binomial Theorem for \( (x + y)^n + (x - y)^n \). 2. **Apply the Binomial Theorem**: The expansion of \( (x + y)^n + (x - y)^n \) can be expressed as: \[ 2 \left( \binom{n}{0} x^n y^0 + \binom{n}{2} x^{n-2} y^2 + \binom{n}{4} x^{n-4} y^4 + \ldots \right) \] Here, \( n = 5 \). 3. **Calculate the coefficients**: - \( \binom{5}{0} = 1 \) - \( \binom{5}{2} = 10 \) - \( \binom{5}{4} = 5 \) 4. **Substitute and simplify**: \[ (2 + \sqrt{5})^5 + (2 - \sqrt{5})^5 = 2 \left( \binom{5}{0} 2^5 + \binom{5}{2} 2^3 (\sqrt{5})^2 + \binom{5}{4} 2^1 (\sqrt{5})^4 \right) \] \[ = 2 \left( 1 \cdot 32 + 10 \cdot 8 \cdot 5 + 5 \cdot 2 \cdot 25 \right) \] \[ = 2 \left( 32 + 400 + 250 \right) \] \[ = 2 \cdot 682 = 1364 \] ### (ii) Evaluate \( (\sqrt{3} + 1)^5 - (\sqrt{3} - 1)^5 \) 1. **Identify the binomial terms**: Let \( x = \sqrt{3} \) and \( y = 1 \). We will use the Binomial Theorem for \( (x + y)^n - (x - y)^n \). 2. **Apply the Binomial Theorem**: The expansion of \( (x + y)^n - (x - y)^n \) can be expressed as: \[ 2 \left( \binom{n}{1} x^{n-1} y + \binom{n}{3} x^{n-3} y^3 + \ldots \right) \] Here, \( n = 5 \). 3. **Calculate the coefficients**: - \( \binom{5}{1} = 5 \) - \( \binom{5}{3} = 10 \) 4. **Substitute and simplify**: \[ (\sqrt{3} + 1)^5 - (\sqrt{3} - 1)^5 = 2 \left( \binom{5}{1} (\sqrt{3})^4 \cdot 1 + \binom{5}{3} (\sqrt{3})^2 \cdot 1^3 \right) \] \[ = 2 \left( 5 \cdot 9 + 10 \cdot 3 \right) \] \[ = 2 \left( 45 + 30 \right) = 2 \cdot 75 = 150 \] ### Show that \( (\sqrt{3} + 1)^5 \) lies between 152 and 153 1. **Using the result from (ii)**: We found that: \[ (\sqrt{3} + 1)^5 - (\sqrt{3} - 1)^5 = 150 \] Therefore, we can express: \[ (\sqrt{3} + 1)^5 = (\sqrt{3} - 1)^5 + 150 \] 2. **Estimate \( (\sqrt{3} - 1)^5 \)**: Since \( \sqrt{3} \approx 1.732 \), we have: \[ \sqrt{3} - 1 \approx 0.732 \] Now, calculate \( (0.732)^5 \): \[ (0.732)^5 \approx 0.184 \] 3. **Combine the results**: \[ (\sqrt{3} + 1)^5 \approx 0.184 + 150 \approx 150.184 \] 4. **Conclusion**: Since \( 150.184 \) lies between \( 152 \) and \( 153 \), we can conclude: \[ 152 < (\sqrt{3} + 1)^5 < 153 \]
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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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