9th Class Mathematics Polynomials Question Bank Polynomials

  • question_answer
    If\[{{(x-1)}^{7}}={{a}_{7}}{{x}^{7}}+{{a}_{6}}{{x}^{6}}+{{a}_{5}}{{x}^{5}}+....+{{a}_{1}}x+{{a}_{0}}\], what is the value of \[{{a}_{7}}+{{a}_{6}}+{{a}_{5}}+....+{{a}_{1}}+{{a}_{0}}\]?

    A)  \[0\]                            

    B)         \[1\]                

    C)         \[128\]                         

    D)         \[64\]               

    Correct Answer: A

    Solution :

    Given \[{{(x-1)}^{7}}={{a}_{7}}{{x}^{7}}+{{a}_{6}}{{x}^{6}}+......+{{a}_{1}}x+{{a}_{0}}\]Since the given polynomial terms are in expression, form Pacal?s triangle we get the coefficients of 1st four terms. Symmetrical to those of the last four terms. \[\Rightarrow \]\[{{(x-1)}^{7}}={{x}^{7}}-7{{x}^{6}}+21{{x}^{5}}-35{{x}^{4}}+35{{x}^{3}}-\] \[21{{x}^{2}}+7x-1=0\] \[\Rightarrow \]\[{{a}_{7}}+{{a}_{6}}+{{a}_{5}}.....+{{a}_{1}}+{{a}_{0}}\] \[=1-7+21-35+35-21+7-1=0\] 


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