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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: Tính bằng cách thuận tiện: a) 26 x (27 + 34) – 27 x (26 + 34) b) 1992 + (-53 + 158) – (247 + 1592) c) 37 x 72 – 37 x 69 – 37 x 3 d) 200

Toán Lớp 6: Tính bằng cách thuận tiện:
a) 26 x (27 + 34) – 27 x (26 + 34)
b) 1992 + (-53 + 158) – (247 + 1592)
c) 37 x 72 – 37 x 69 – 37 x 3
d) 2001 – (53 + 1579) – (-53)
e) (-29) x (85 – 47) – 85 x (47 – 29)

Comments ( 2 )

  1.  $\text{a, 26 x ( 27 + 34)- 27 x(26 + 34)}$
    $\text{= ( 26 x 27 )+(26 x 34) + ( -27 x 26 ) + ( -27 x 34 )}$
    $\text{= [(26 x 27 ) + ( -27 x 26 )] + [(26 x 34) + ( -27 x 34}$
    $\text{= 0 + 0 = 0}$
     $\text{b, 1992 + ( -53 + 168 ) – ( 247 + 1592)}$
    $\text{= 1992 -53 + 168 – 247 – 1592}$
    $\text{= ( 1992 – 1592) – ( 53 + 247) + 158}$
    $\text{= 400 – 300 + 158 = 258}$
      $\text{c, 37 x 72 – 37 x 69 – 37 x 3}$
    $\text{= 37 x ( 72 – 69 – 3 ) = 37 x 0 = 0 }$
      $\text{d, 2001 – ( 53 + 1579) – ( – 53)}$
    $\text{= 2001 – 53 – 1579 + 53}$
    $\text{= ( 2001 – 1579 ) + ( -53 + 53)}$
    $\text{= 422 + 0 = 922}$
      $\text{e, ( ( -29) x ( 85 – 47) – 85 x ( 47 – 29)}$
    $\text{= (-29 x 85) + [(-29) x (-47)] + [(-85)x47] + [(-85)x(-29)]}$
    $\text{= {( -29 x 85 +[(-85)x(-29]} + {[(-29) x (-47)] + [(-85)x47]}}$
    $\text{= 0 + ( – 2632) = -2632}$

  2. Lời giải chi tiết:
    a) 26.(27+34)-27.(26+34)
    =26.27+26.34-27.26-27.34
    =(26.27-27.26)+(26.34-27.34)
    =26.(27-27)+34.(26-27)
    =26.0+34.(-1)
    =0+(-34)
    =-34
    b) 1992+(-53+158)-(247+1592)
    =1992-53+158-247-1592
    =(1992-1592)-(53+247)+158
    =400-200+158
    =200+158
    =358
    c) 37.72-37.69-37.3
    =37.(72-69-3)
    =37.0
    =0
    d) 2001-(53+1579)-(-53)
    =2001-53-1579+53
    =(2001-1579)+(53-53)
    =422+0
    =422
    e) (-29).(85-47)-85.(47-29)
    =-29.85+29.47-85.47+85.29
    =(-29.85+85.29)+(29.47-85.47)
    =85.(-29+29)+47.(29-85)
    =85.0+47.(-56)
    =0+(-2632)
    =-2632

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222-9+11+12:2*14+14 = ? ( )