25/2

181/5

247/2

71/5

a)`1,25 + 1,25 xx 2 + 7 xx 1,25=1,25 xx (1+2+7) = 1,25 xx 10 =12,5`

b)`3,62xx12–2xx0,362xx10=3,62 xx 12 -2 xx 3,62=3,62xx(12-2)=3,62xx10=36,2`

c)`12,35xx15–1,235xx10xx6+12,35=12,35xx15–12,35xx6+12,35=12,35xx(15-6+1)=12,35xx10=123,5`    

d)`1,42 : 0,5 + 1,42 xx 8=1,42xx2+1,42xx8=1,42xx(2+8)=1,42xx10=14,2`

Chắc ý you là:

tính bằng cách thuận tiện nhất 2,84 x 1,4 + 15,2 x 1,42 + 2,84 - 0,284 : 0,1

?

hello

tự mà làm

(450 x 27) : 50

=(450:50)x27

=9x27

=243

\(\left(450\times27\right):50=\left(450:50\right)\times27=9\times27=243\)

\(\text{( 450 x 27 ) : 50}\)

\(=\text{(450:50) x27}\)

\(\text{=9x27}\)

\(\text{=243}\)

12,35 + 1,42 - 11,35 + 8,58

= (12,35 - 11,35) + (1,42 + 8,58)

= 1 + 10

= 11

12,35 + 1,42 - 11,35 + 8,58 
= 12,35 + (1,42 - 11,35 ) + 8,58 
= 12,35 - 9,93 + 8,58 
= 2,42 + 8,58 
= 11

\(4,7\cdot8+4,7:0,5\)

\(=4,7\cdot8+4.7\cdot2\)

\(=4,7\left(8+2\right)\)

\(=4,7\cdot10=47\)

mn giải nhanh giùm em nhé

= ( 2 , 5 x 0, 5) x ( 12 , 5 x 8 ) 

=        1,25   x 100 

=           125

\(2,5\times12,5\times8\times0,5\)

\(=\left(2,5\times0,5\right)\times\left(12,5\times8\right)\)

\(=1,25\times100\)

\(=125\)

\(1,25:0,5+1,25\times8\\ =1,25\times2+1,25\times8\\ =1,25\times\left(2+8\right)\\ =1,25\times10\\ =12,5\)

  0,75 + 1,5 \(\times\) 97,8 \(\times\) 0,5 + 0,25 \(\times\) 3 \(\times\) 1,2

= 0,75 \(\times\) 1 + (1,5 \(\times\) 0,5)\(\times\) 97,8 + (0,25 \(\times\)3) \(\times\) 1,2

= 0,75 \(\times\) 1 + 0,75 \(\times\) 97,8 + 0,75 \(\times\) 1,2

= 0,75 \(\times\) ( 1 + 97,8 + 1,2)

= 0,75 \(\times\) [1 + ( 97,8 + 1,2)]

= 0,75 \(\times\) [1 + 99]

= 0,75 \(\times\) 100

= 75