\(18.15+35+15.32+35.4+9\)

\(=\left(18.15+15.32\right)+\left(35+35.4\right)+9\)

\(=\left[15.\left(18+32\right)\right]+\left[35.\left(1+4\right)\right]+9\)

\(=\left[15.50\right]+\left[35.5\right]+9\)

\(=750+175+9\)

\(=934\)

= 454.46875

\(18.15+35+15.32+35.4+9\)

\(=15.\left(18+32\right)+35.\left(1+4\right)+9\)

\(=15.50+35.5+9\)

\(=15.50+\left(15+20\right).5+9\)

\(=15.50+15.5+20.5+9\)

\(=15.\left(50+5\right)+100+9\)

\(=15.55+109\)

\(=825+109=934\)

18. 25 + 35 + 15. 32 + 35. 49

=450+35+480+1715

=485+480+1715

=965+1715

=2680

Ta có:

18.25 + 35 + 15.32 + 35.49

= 450 + 35 + 480 + 1715

= 2680

18. 25 + 35 + 15. 32 + 35. 49

=450+35+480+1715

=485+480+1715

=965+1715

=2680

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

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

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

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

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

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

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

= 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).

a) \(\dfrac{3}{35}+\dfrac{7}{20}+\dfrac{32}{35}+\dfrac{13}{20}\)

Áp dụng tính chất giao hoán, kết hợp của phép cộng, ta được:

\(\left(\dfrac{3}{35}+\dfrac{32}{35}\right)+\left(\dfrac{7}{20}+\dfrac{13}{20}\right)\)

\(=1+1\)

\(=2\)

b) \(\dfrac{18\cdot15\cdot56}{42\cdot27\cdot25}=\dfrac{2\cdot3\cdot3\cdot5\cdot3\cdot4\cdot2\cdot7}{2\cdot3\cdot2\cdot2\cdot3\cdot9\cdot5\cdot5}\)

\(=\dfrac{2\cdot2\cdot3\cdot3\cdot3\cdot4\cdot5\cdot7}{2\cdot2\cdot2\cdot3\cdot3\cdot5\cdot5\cdot9}=\dfrac{3\cdot2\cdot2\cdot7}{2\cdot5\cdot9}=\dfrac{42}{45}\)

a) \(36.\left(-57\right)-57.64\)

\(=36.\left(-57\right)+\left(-57\right).64=\left(-57\right).\left(36+64\right)\)

\(=\left(-57\right).100=-5700\)

b)\(32.\left(-17\right)+\left(-18\right).17-50.13\)

\(=\left(-32\right).17+\left(-18\right).17-50.13\)

\(=17.\left(-32-18\right)-50.13=17.\left(-50\right)+\left(-50\right).13\)

\(=\left(-50\right).\left(17+13\right)=\left(-50\right).30=-150\)

c)\(-\left(-35\right)+12-|-35|-42\)

\(=35+12-35-42=12-42=-30\)

d)\(\left(-15-12\right):\left(-3\right)^2+5-13.\left(-2\right)+\left(-64\right):2^3\)

\(=-27:9+5+26-64:8=-3+5+26-8=20\)

e)\(\left(135-35\right).\left(-37\right)+37.\left(-42-58\right)=100.\left(-37\right)+37.\left(-100\right)\)

\(=\left(-100\right).37+37.\left(-100\right)=\left(-100\right).\left(37+37\right)\)

\(=\left(-100\right).74=-7400\)

Chúc em học tốt!!!!!!

Giải thích gõ mỏi tay lắm nên mình chỉ ghi đáp án thôi nha !!!

a)-5700

b)-1500

c)-30

d)20

d)-7400

₁₎ ( 2002 - 79 + 15 ) - ( -79 + 15 ) = 2002 

₂₎ - (515 - 80+ 91 ) - ( 2003 + 80 + 91 ) = -2700 

₃₎ 4573 + 46 - 4573 + 35 - 16 - 5 = 60

₄₎ 32 + 34 + 36 + 38 - 10 - 12 - 14 - 16 - 18 = 70 

a) 15 . (27 + 18 + 6 ) + 15 . ( 23 +12 ) =  15. 51 + 15 . 35 = 765 + 525 = 1290

b) 14 . 35 . 5 + 10 . 25 . 7 + 20 . 70 = 2450 + 1750 + 1400 = 2452450

c) 53 . ( 51 + 4 ) + 53 . ( 49  + 96 ) + 53 = 53 . 55 + 53 . 145 + 53 = 2915 . 7685 = 22401775

d) 46 . ( 27 +75 ) +8 . ( 58 + 25 ) + 8 . ( 58 + 25 ) . 2 = 46 . 102 + 8 . 83 + 8 . 83 =  4692 + 664 + 664 = 6020

Bài 7:

a) = 35 + 75 + 345 - 35 - 75

    = 345

b) = 2002 - 75 + 15 + 79 - 15

    = 2006

c) = - 515 + 80 - 91 - 2003 - 80 + 91

    = -2518

Bài 8:

a) = (4573 + 4573) + (46 - 16) + (35 - 5)

    = 9146 + 30 + 30

    = 9206

b) = (32 + 38) + (34+36) - (12+18) - (14+16) - 10

    = 70 + 70 - 30 - 30 - 10

    = 70

BÀI 7

a) (37+75)+(345-35-75)

=345

b) (2002-75+15)-(-79+15)

=2002

c) -(515-80+91)-(2003+80-91)

=-2518

BÀI 8 

a)4573+46+4573+35-16-5

=(4573+4573)+(46-10)+(35-5)

=9146+30+30

=9206

b) có 2 cách

bạn có thể làm theo cáchVũ Như Mai hoặc theo cách của mình

=32+34+36+38-10-12-14-16-18

=(32-12)+(34-14)+(36-16)+(38-18)-10

=20+20+20+20-10

=80-10=70