\(a.=\dfrac{2019}{2020}\times\left(\dfrac{4}{11}+\dfrac{5}{11}+\dfrac{2}{11}\right)\\ =\dfrac{2019}{2020}\times1=\dfrac{2019}{2020}\\ b.=\dfrac{25}{27}\times\left(\dfrac{17}{14}-\dfrac{1}{14}-\dfrac{2}{14}\right)\\ =\dfrac{25}{27}\times1=\dfrac{25}{27}\)

Thanks mik chữ cũng hơi ẩu

= ( -25) x 1 +72 x (-25) + (-25) x27

= (- 25) x ( 1 + 72 + 27 )

= (-25) x 100

=-2500 

b 

c 37 x ( 25 + 37 ) - 27 x ( 37 + 25 )

= 37 x 25 + 37 x 37 -27x37 -27x25

= ( 37 x25 -27x25 )+(37x37-27+37)

=25 x ( 37 -27 ) + 37 x (37 - 27)

= 25 x10 + 37x10 

= 250 + 370 

= 770

a) =-25.( 1+72+27)

=-25.100= - 2500

b) = -36.45 + (-36) . 15 - (-36) . 40

= - 36. ( 45+15-40)

= -36 . 20= -720

c) =37.62 - 27 .62

= 62. ( 37 - 27 )

= 62 . 10 

= 620

chịu

\(\Leftrightarrow\dfrac{29-x}{21}+1+\dfrac{27-x}{23}+1+\dfrac{25-x}{25}+1+\dfrac{23-x}{27}+1=0\)

\(\Leftrightarrow\dfrac{50-x}{21}+\dfrac{50-x}{23}+\dfrac{50-x}{25}+\dfrac{50-x}{27}=0\)

\(\Leftrightarrow\left(50-x\right)\left(\dfrac{1}{21}+\dfrac{1}{23}+\dfrac{1}{25}+\dfrac{1}{27}\ne0\right)=0\Leftrightarrow x=50\)

\(\dfrac{29-x}{21}+\dfrac{27-x}{23}+\dfrac{25-x}{25}+\dfrac{23-x}{27}=-4\\ \Leftrightarrow\left(\dfrac{29-x}{21}+1\right)+\left(\dfrac{27-x}{23}+1\right)+\left(\dfrac{25-x}{25}+1\right)+\left(\dfrac{23-x}{27}+1\right)=0\\ \Leftrightarrow\dfrac{50-x}{21}+\dfrac{50-x}{23}+\dfrac{50-x}{25}+\dfrac{50-x}{27}=0\\ \Leftrightarrow\left(50-x\right)\left(\dfrac{1}{21}+\dfrac{1}{23}+\dfrac{1}{25}+\dfrac{1}{27}\right)=0\\ \Leftrightarrow50-x=0\left(vì.\dfrac{1}{21}+\dfrac{1}{23}+\dfrac{1}{25}+\dfrac{1}{27}\ne0\right)\\ \Leftrightarrow x=50\)

-35 

ko biết 

(25* 4+ 27* 5 )* (100-25 *4 )

=275 *(25*4 ) -100

=275* 0

=0

Lời giải:

$(25\times 4+27\times 5)\times (100-25\times 4)=(25\times 4+27\times 5)\times 0$

$=0$

( 25 x 4 + 27 x 5 ) x ( 100 - 25 x 4 )

= ( 25 x ( 4 + 5 )) x ( 100 - 100 )

=  ( 25 x 9 ) x  0

= 225 x 0

= 0

học tốt nha 

3.54 X 73 + 0.23 X 25 + 3.54 X 27 +0.77 X 25

= 3.54X(73+27)+25X(0.23+0.77)

=354+25

=400

3,54.73+0,23.25+3,54.27+0,77.25

=(3,54.73+3,54.27)+(0,23.25+0,77.25)

=3,54.(73+27)+25.(0,23+0,77)

=3,54.100+25.1

=379

3,54 x 73 + 0,23 x 25 + 3,54 x 27 + 0,17 x 25

= 3,54 x ( 73 + 27 ) + 25 x ( 0,23 + 0,17 )

= 3,54 x 100 + 25 x 0,4 

= 354 + 10

= 364

=3.54x(73+27)+25x(0.23+0.17)

=3.54x100+25x0.4

=354+10

=364

(k mk nha bn )

Trả lời

3,54 x 73 + 0,23 x 25 + 3,54 x 27 + 0,17 x 25

=3,54 x ( 73 + 27 ) + 25 x ( 0,23 + 0,17 )

= 3,54 x 100 + 25 x 0,4

= 354 + 10

= 364