Tính Nhanh a, 34 . 23 + 23 . 65 + 99 b, $\frac{135 . 1420 – 45 . 780 . 3}{3 + 6 + 9+…+24+27}$ c, $\frac{2010.2012-538}{1472+2010.2011}$

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Tính Nhanh
a, 34 . 23 + 23 . 65 + 99
b, $\frac{135 . 1420 – 45 . 780 . 3}{3 + 6 + 9+…+24+27}$
c, $\frac{2010.2012-538}{1472+2010.2011}$

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Maya 2 tháng 2021-07-19T11:30:36+00:00 1 Answers 1 views 0

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    2021-07-19T11:32:13+00:00

    Đáp án:$a)2300$ $b)640$ $c) 1$

     

    Giải thích các bước giải:

     a)$34.23+23.65+99=23.(34+65)+99=23.99+99=23.(99+1)=23.100=2300$
    b)$\dfrac{135.1420-45.780.3}{3+6+9+..+27}=\dfrac{3.45.(1420-780)}{3(1+2+..+9)}$
    $=\dfrac{3.45.640}{3.45}=640$
    c)$\dfrac{2010.2012-538}{1472+2010.2011}$
    =$\dfrac{(2011-1)(2011+1)-538}{1472+2011(2011-1)}$
    =$\dfrac{2011^2-1-538}{2011^2+1472-2011}$
    =$\dfrac{2011^2-539}{2011^2-539}=1$

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