câu 1 = -68

câu 2 =-2500

câu 3=168

câu 4 =4571

câu 6=124

a.\(M=\left\{5n|n\in N,n\le5\right\}\)

b.\(P=\left\{n^2|n\in N^{\text{*}},n\le9\right\}\)

c.\(N=\left\{3n+1|n\in N,n\le7\right\}\)

\(\dfrac{8}{5}\cdot\dfrac{45}{17}\cdot\dfrac{-25}{16}\cdot\dfrac{-34}{9}=\dfrac{8\cdot5\cdot9\cdot25\cdot17\cdot2}{5\cdot17\cdot8\cdot2\cdot9}=\dfrac{25}{9}\) (bỏ đi các dấu trừ vì số âm nhân số âm là số dương)

44 . -36 + 22 . -28

= ( 22 . 2 ). -36 + 22 . -28 

=  22 . ( 2 . -36 ) + 22 . -28

=    22 . -72 + 22 . -28

=           22 . ( -72 + -28 )

=           22  . -100

=             - 2200 

44 . (-36) + 22 . (-28)

= [44 . (-36) + [22 . (-28)

= (-1584) + (-616)

= -2200

44.(-36)+22.(-28)=[44.(-36)]+[22.(-28)]

= (-1584)+(-616)

=-2200

1.

\(35\times\left(14-23\right)-23\times\left(14-35\right)\)

\(=35\times14-35\times23-23\times14+23\times35\)

\(=\left(23\times35-35\times23\right)+14\times\left(35-23\right)\)

\(=0+14\times12\)

\(=168\)

2.

\(27\times\left(13-16\right)-16\times\left(13-27\right)\)

\(=27\times13-27\times16-16\times13+16\times27\)

\(=13\times\left(27-16\right)+\left(27\times16-16\times27\right)\)

\(=13\times11+0\)

\(=143\)

3.

\(44\times\left(-36\right)+22\times\left(-28\right)\)

\(=22\times2\times\left(-36\right)+22\times\left(-28\right)\)

\(=22\times\left(-72\right)+22\times\left(-28\right)\)

\(=22\times\left[\left(-72\right)+\left(-28\right)\right]\)

\(=22\times\left(-100\right)\)

\(=-2200\)

Chúc bạn học tốt

\(\dfrac{7}{19}x\dfrac{8}{23}+\dfrac{7}{19}x\dfrac{15}{23}+1\dfrac{7}{19}\)

= \(\dfrac{7}{19}x\left(\dfrac{8}{23}+\dfrac{15}{23}\right)+1+\dfrac{7}{19}\)

=\(\dfrac{7}{19}x1+1+\dfrac{7}{19}\)

= \(\dfrac{7}{19}+1+\dfrac{7}{19}=1\dfrac{14}{19}\) = \(\dfrac{33}{19}\)

\(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{3}{21}-\dfrac{17}{32}\)

=  \(\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{1}{7}-\dfrac{17}{32}\)

= \(\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{49}{32}-\dfrac{17}{32}\right)\)

= 1 + 1 + 1 = 3

\(\dfrac{8}{9}x\dfrac{15}{16}x\dfrac{24}{25}x\dfrac{35}{36}x\dfrac{48}{49}x\dfrac{63}{64}\)

= \(\dfrac{3}{4}\) *Câu này bạn tự sử dụng gạch nhé!

`1,`

`a,`

`7/19 \times 8/23 + 7/19 \times 15/23 + 1 7/19`

`= 7/19 \times 8/23 + 7/19 \times 15/23 + 1 + 7/19`

`= 7/19 \times (8/23 + 15/23 + 1) + 1`

`= 7/19 \times 2 + 1`

`=14/19 + 1`

`= 33/19`

`b,`

`75/100 + 18/21 + 49/32 + 1/4 + 3/21 - 17/32`

`= 75/100 + (18/21 + 3/21) + (49/32 - 17/32) + 1/4`

`= 0,75 + 1 + 1 + 0,25`

`= (0,75 + 0,25) + 1 + 1`

`= 1+1+1=3`

`c,`

`8/9 \times 15/16 \times 24/25 \times 35/36 \times 48/49 \times 63/64`

`=` \(\dfrac{2\times3}{3\times3}\times\dfrac{3\times5}{4\times4}\times\dfrac{3\times4\times2}{5\times5}\times\dfrac{5\times7}{6\times6}\times\dfrac{6\times8}{7\times7}\times\dfrac{7\times9}{8\times8}\)

`= 3/4` (bạn sử dụng gạch, rút gọn các số là được nhé).

\(B=\dfrac{-1}{9}\cdot\dfrac{-17}{19}\cdot\dfrac{58}{51}=\dfrac{1}{9}\cdot\dfrac{1}{3}\cdot\dfrac{58}{13}=\dfrac{58}{351}\)

\(\dfrac{45.21.25}{7.15.36}=\dfrac{3.3.3.5.7.5.5}{7.5.3.3.2.3.2}=\dfrac{25}{4}\)

45\7 x 21\15 x 25/36

=45x21x25/7x15x36

=15x3x7x3x25/7x15x3x12

=3x25/12

=75/12

=25/4