RAJASTHAN ­ PET Rajasthan PET Solved Paper-2002

  • question_answer
    \[^{47}{{C}_{4}}+\sum\limits_{i=1}^{5}{^{52-i}{{C}_{3}}}\]is equal to

    A)  \[^{50}{{C}_{4}}\]

    B)  \[^{50}{{C}_{4}}\]

    C)  \[^{10}{{C}_{5}}\]

    D)  \[^{52}{{C}_{6}}\]

    Correct Answer: D

    Solution :

     \[^{47}{{C}_{4}}+\sum\limits_{i=1}^{5}{^{52-i}{{C}_{3}}}\] \[{{=}^{47}}{{C}_{4}}{{+}^{51}}{{C}_{3}}{{+}^{50}}{{C}_{3}}{{+}^{49}}{{C}_{3}}{{+}^{48}}{{C}_{3}}{{+}^{47}}{{C}_{3}}\] \[{{=}^{47}}{{C}_{4}}{{+}^{47}}{{C}_{3}}{{+}^{48}}{{C}_{3}}{{+}^{49}}{{C}_{3}}{{+}^{50}}{{C}_{3}}{{+}^{51}}{{C}_{3}}\] \[{{=}^{48}}{{C}_{4}}{{+}^{48}}{{C}_{3}}{{+}^{49}}{{C}_{3}}{{+}^{50}}{{C}_{3}}{{+}^{51}}{{C}_{3}}\] \[{{=}^{49}}{{C}_{4}}{{+}^{49}}{{C}_{3}}{{+}^{50}}{{C}_{3}}{{+}^{51}}{{C}_{3}}\] \[{{=}^{50}}{{C}_{4}}{{+}^{50}}{{C}_{3}}{{+}^{51}}{{C}_{3}}\] \[{{=}^{51}}{{C}_{4}}{{+}^{51}}{{C}_{3}}\] \[{{=}^{52}}{{C}_{4}}\]


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