a, Ta có:
1996 + 3992 + 5988 + 7984
= 1 x 1996 + 2 x 1996 + 3 x 1996 + 4 x 1996
= (1 + 2 + 3 + 4) x 1996
= 10 x 1996
= 19960
b, 2 x 3 x 4 x 8 x 50 x 25 x 125
= 3 x 2 x 4 x 50 x 8 x 25 x 125
= 3 x (2 x 50) x (4 x 25) x (8 x 125)

= 30 000 000.

a) 14924

b) 30000000

c) 0

A=19924

B=30000000

C=0

Ta nhận thấy :

45 x 128 – 90 x 64 = 45 x (2 x 64) – 90 x 64

          = (45 x 2) x 64 – 90 x 64

          = 90 x 64 – 90 = 0

Trong 1 tích có 1 thừa số bằng 0. Vậy tích đó bằng 0, tức là :

(45 x 46 + 47 x 48) x (51 x 52 – 49 x 48) x (45 x 128 – 90 x 64) x (1995 x 1996 + 1997 x 1998) = 0

c, Ta nhận thấy:
45 x 128 – 90 x 64 = 45 x (2 x 64) – 90 x 64
= (45 x 2) x 64 – 90 x 64
= 90 x 64 – 90 = 0
Trong 1 tích có 1 thừa số bằng 0. Vậy tích đó bằng 0, tức là:

(45 x 46 + 47 x 48) x (51 x 52 – 49 x 48) x (45 x 128 – 90 x 64) x (1995 x 1996 + 1997 x 1998) = 0

\(a,50\%+\dfrac{7}{12}-\dfrac{1}{2}\\ =\dfrac{1}{2}+\dfrac{7}{12}-\dfrac{1}{2}\\ =\left(\dfrac{1}{2}-\dfrac{1}{2}\right)+\dfrac{7}{12}\\ =\dfrac{7}{12}\\ b,2022\times67+2022\times43-2022\times10\\ =2022\times\left(67+43-10\right)\\ =2022\times100\\ =202200.\\ c,125-25:3\times12\)

\(=25\times5-25:3\times12\\ =25\times\left(5-\dfrac{1}{3}\right)\times12\\ =25\times\dfrac{14}{3}\times12\\ =1400\)

a,50%+127​−21​=21​+127​−21​=(21​−21​)+127​=127​b,2022×67+2022×43−2022×10=2022×(67+43−10)=2022×100=202200.c,125−25:3×12

$=25\times 5-25:3\times 12=25\times \left(5-\genfrac{}{}{0ex}{}{1}{3}\right)\times 12=25\times \genfrac{}{}{0ex}{}{14}{3}\times 12=1400$

a ) 2 x 3 x 4 x 8 x 50 x 25 x 125

  = 3 x 2 x 50 x 4 x 25 x 8 x 125

  = 3 x ( 2 x 50 ) x ( 4 x 25 ) x ( 8 x 125 )

  = 3 x 100 x 100 x 1000

  = 30000000

b ) 45 x 128 - 90 x 64

  = 45 x ( 2 x 64 ) - 90 x 64

  = ( 45 x 2 ) x 64 - 90 x 64

  = 90 x 64 - 90 x 64

  = 0

a) = (2.50).(4.25).(8.125).3=100.100.1000.3=30000000

b)45.128-90.64=45.128-45.2.64

=45.128-45.128

=0

(2x50)+(4x25)+(125x8) x3 = 3300

c) 25

a) 19,17x25x4=19,17(25x4)=19,17x100=1917

b)1,79x(8x125)=1,79x1000=1790

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