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Find the term independent of x in the ex...

Find the term independent of `x` in the expansion of the following binomials:
`(2x^(2) - (1)/(x) )^12` What is its value?

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To find the term independent of \( x \) in the expansion of \( (2x^2 - \frac{1}{x})^{12} \), we will follow these steps: ### Step 1: Identify the General Term The general term \( T_{r+1} \) in the expansion of \( (a + b)^n \) is given by: \[ T_{r+1} = \binom{n}{r} a^{n-r} b^r \] In our case, we have: - \( n = 12 \) - \( a = 2x^2 \) - \( b = -\frac{1}{x} \) ### Step 2: Write the General Term Substituting the values into the formula, we get: \[ T_{r+1} = \binom{12}{r} (2x^2)^{12-r} \left(-\frac{1}{x}\right)^r \] This simplifies to: \[ T_{r+1} = \binom{12}{r} (2^{12-r} (x^2)^{12-r}) \left(-1^r \cdot x^{-r}\right) \] \[ = \binom{12}{r} (-1)^r 2^{12-r} x^{2(12-r) - r} \] \[ = \binom{12}{r} (-1)^r 2^{12-r} x^{24 - 3r} \] ### Step 3: Find the Term Independent of \( x \) For the term to be independent of \( x \), the exponent of \( x \) must be zero: \[ 24 - 3r = 0 \] Solving for \( r \): \[ 3r = 24 \implies r = 8 \] ### Step 4: Identify the Term The term independent of \( x \) corresponds to \( r = 8 \), which is the \( (8 + 1) \)th term, or the 9th term: \[ T_{9} = \binom{12}{8} (-1)^8 2^{12-8} \] ### Step 5: Calculate the Value of the Term Now we calculate: \[ T_{9} = \binom{12}{8} \cdot 2^4 \] Using the property \( \binom{n}{r} = \binom{n}{n-r} \): \[ \binom{12}{8} = \binom{12}{4} = \frac{12!}{4!(12-4)!} = \frac{12 \times 11 \times 10 \times 9}{4 \times 3 \times 2 \times 1} = \frac{11880}{24} = 495 \] Now substituting back: \[ T_{9} = 495 \cdot 16 = 7920 \] ### Conclusion The term independent of \( x \) in the expansion of \( (2x^2 - \frac{1}{x})^{12} \) is \( 7920 \). ---
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ICSE-BINOMIAL THEOREM-EXERCISE 13 (b)
  1. Find the term independent of x in the expansion of the following binom...

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  2. Find the term independent of x in the expansion of the following binom...

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  3. Find the term independent of x in the expansion of the following binom...

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  4. Find the coefficient of (i) a^(6) b^(3) in the expansion of (2a - (b...

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  5. Find the coefficient of (ii) x^7 in the expansion of (x^(2) + (1)/(x...

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  6. Find the coefficient of (iii) (1)/(x^(17) ) in the expansion of (x^(...

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  7. Find the coefficient of (iv) x^4 in the expansion of ((x)/(2) - (3)/...

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  8. If the coefficients of x^2 and x^3 in the expansion of (3 + ax)^(9) ar...

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  9. Write down the fourth term in the binomial expansion of (px + (1)/(x) ...

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  10. The expansion by the binomial theorem of (2 x + (1)/(8) )^(10) is 1024...

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  11. The expansion by the binomial theorem of (2 x + (1)/(8) )^(10) is 1024...

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  12. The expansion by the binomial theorem of (2 x + (1)/(8) )^(10) is 1024...

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  13. Find the coefficient of x^7 in ( ax^(2) + (1)/( bx) )^(11) and the coe...

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  14. In a binomial expansion, ( x+ a)^(n), the first three terms are 1, 56 ...

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  15. Write the 4th term from the end in the expansion of ((x^3)/( 2) - (2)/...

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  16. The coefficients of (2r +1)th and (r+2)th terms in the expansions of (...

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  17. The coefficient of the middle term in the binomial expansion in powers...

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  18. Find the sixth term of the expansion of (y^(1//2) + x^(1//3) )^(n), if...

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  19. Show that the coefficient of the middle term in the expansion of (1 + ...

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  20. Show that the middle term in the expansion of (1+ x)^(2n) is (1.3.5…(...

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