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The coefficient of `x^(28)`in the expansion of `(1+x^3-x^6)^(30)`is`1`b. `0`c. `^30 C_6`d. `^30 C_3`A. 1B. 0C. `.^(30)C_(6)`D. `.^(30)C_(3)` |
Answer» Correct Answer - B `(1+x^(3)-x^(6))^(30)` `= {1+x^(3)(1-x^(3))}^(30)` `=.^(30)C_(0) + .^(30)C_(1)x^(3)(1-x^(3))+.^(30)C_(2)x^(6)(1-x^(3))^(2) + "…."` Obviously, each term will contain `x^(3m), m in N`. But 28 is not divisible by 3. Therefore ther will be no term containing `x^(28)`. |
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