Làm giúp mẹ mình bài 1 và 2 nha

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Làm giúp mẹ mình bài 1 và 2 nha
lam-giup-me-minh-bai-1-va-2-nha

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Khang Minh 1 year 2020-11-22T11:37:19+00:00 1 Answers 73 views 0

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    0
    2020-11-22T11:38:59+00:00

    Đáp án:

    $1)
    a) 27\\
    b) \dfrac{512}{23}\\
    c)
    \dfrac{-4}{7}$

    Giải thích các bước giải:

    $1)
    a) 3^2.\dfrac{1}{243}.81^2.\dfrac{1}{3^2}\\
    =\dfrac{3^2}{3^5}.\dfrac{(3^4)^2}{3^2}\\
    =\dfrac{1}{3^3}.\dfrac{3^8}{3^2}\\
    =\dfrac{3^8}{3^5}\\
    =3^3\\
    =27\\
    b) (4.2^5).(2^3.\dfrac{1}{46}\\
    =2^2.2^5\dfrac{2^3}{2.23}\\
    =\dfrac{2^7.4}{23}\\
    =\dfrac{512}{23}\\
    c)
    \dfrac{4^6.9^5+6^9.120}{-8^4.3^{12}-6^{11}}\\
    =\dfrac{(2^2)^6.(3^2)^5+(2.3)^9.2^3.3.5}{-(2^3)^4.3^{12}-(2.3)^{11}}\\
    =\dfrac{2^{12}.3^{10}+2^9.3^9.2^3.3.5}{-2^{12}.3^{12}-2^{11}.3^{11}}\\
    =\dfrac{2^{12}.3^{10}+2^{12}.3^{10}.5}{-2^{12}.3^{12}-2^{11}.3^{11}}\\
    =\dfrac{2^{12}.3^{10}(1+5)}{-2^{11}.3^{11}(2.3+1)}\\
    =\dfrac{2.6}{-3.7}\\
    =\dfrac{-4}{7}\\
    2)
    5^5-5^4+5^3\\
    =5^3(5^2-5+1)\\
    =5^3.21$
    Do $21\vdots 7\Rightarrow 21.5^3\vdots 7$
    $\Rightarrow 5^5-5^4+5^3\vdots 7$

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Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )