JEE Main & Advanced Sample Paper JEE Main - Mock Test - 1

  • question_answer
    The last digit in the expansion of \[{{7}^{300}}\] is

    A) 7                    

    B) 9    

    C) 1                    

    D) 3

    Correct Answer: C

    Solution :

    [c]: We have, \[{{7}^{300}}={{({{7}^{2}})}^{150}}={{(50-1)}^{150}}\] \[{{=}^{150}}{{C}_{0}}{{(50)}^{150}}{{(-1)}^{0}}{{+}^{150}}{{C}_{1}}{{(50)}^{149}}{{(-1)}^{1}}+......\]\[{{+}^{150}}{{C}_{150}}{{(50)}^{0}}{{(-1)}^{150}}\] Thus the last digits of \[{{7}^{300}}\]are\[^{150}{{C}_{150}}.1.1\]i.e.,1.


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