cậu dùng máy tính ý vừa nhanh vừa tiện :))

Kết quả = - 790

Khá dễ

k nha!!!

(57 x 162) + (37 x 48) - (62 x 46)

= 9234 + 1776 - 2852

= 11008 - 2852

= 8156

\(57\cdot162+37\cdot162-62\cdot48-62\cdot46\) 

\(=162\left(57+37\right)-62\left(48+46\right)\) 

\(=162\cdot94-62\cdot94\) 

\(=94\left(162-62\right)\) 

\(=94\cdot100=9400\)

            Bài làm :

Ta có :

\(57\times162+37\times162-62\times48-62\times46\)

\(=162\times\left(57+37\right)-62\times\left(48+46\right)\)

\(=162\times94-62\times94\)

\(=94\times\left(162-62\right)\)

\(=94\times100\)

\(=9400\)

Vệ sinh nhà cửa, chặt bỏ bụi rậm, nằm màn

\(=-a-3b-c-4b+c-2a+7b=-3a\)

= a-3b-c-4b+c-2a+7b
= (a-2a)+(-3b-4b+7b)+(-c+c)
= -a

Nào gg thẳng tiến 

308:5,5=56

18,5:7,4=2,5

8,568:36=0,238

8,16:3=2,72

85:14=7(dư 1)

Câu 3:

a: \(25x-30x^2=5x\left(5-6x\right)\)

b: \(8x\left(x+4y\right)+16\left(x+4y\right)=8\left(x+4y\right)\left(x+2\right)\)

c: \(24x^8y^7-15x^6y^5+18x^6y^3\)

\(=3x^6y^3\left(8x^2y^4-5y^2+6\right)\)

câu 1:

a) 4x( 5x + 9 )

 = 4x5x + 4x9

 = 20x²+36x

b) (3x - 2) ( x+7 )

 = 3xx + 3x7 - 2x - 2 . 7

 = 3x²+ 21x - 2x - 14

 = 3x² +19x - 14

c) (2x- 5 )(x²-7x + 4 )

 = 2xx² - 2x7x + 2x4 - 5x² +5 . 7x - 5.4

 = 2x³- 14x²+8x - 5x ²+ 35x - 20

 = 2x³+ ( - 14x²- 5x² )+(8x+35x) - 20

 = 2x³ - 9x² + 43x - 20

Câu 2 :

a) (5x - 3x)²

  = (5x)² - 2.5x3y + (3y)²

  = 25x² - 30xy +9y

b) (2x - 5)(2x + 5)

 = (2x)² - 5²

  = 4x² - 25

c) (3x - 7y)³

 = ( 3x)³ - 3(3x)²7y + 3.3x(7y)² - (7y)²

 = 27x³ - 189x²y + 441xy²- 343y³

d) (x+5)(x²-5x+25)

 = (x+5)(x²-5x+5²)

 = x³+5³

 = x³+125

Câu 3 : 

a) 25x-30x²

 = 5.5x-5.6xx

 = 5x(5-6x)

b) 8x(x+4y)+16(x+4y)

 = (x+4y)(8x+16)

c) 24x⁸y⁷ -15x⁶y⁵+18x⁶y³

 = 3.8x⁶x²y³y⁴-3.5x⁶y³y²+3.6x⁶y³

 = 3x⁶y³(8x²y⁴-5y²+6)

Câu 3: 

a: \(25x-30x^2=5x\left(5-6x\right)\)

b: \(8x\left(x+4y\right)+16\left(x+4y\right)=8\left(x+4y\right)\left(x+2\right)\)

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

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

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

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

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

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

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

= 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).