Động vật, cây cối, sông suối, ao hồ là những vật thể tự nhiên. Sách, vở, ti vi, xe máy, quạt điện là những vật thể nhân tạo

   (2x³ - 3x - 1) . (5x + 2)

= 10x⁴ - 15x² - 5x + 4x³ - 6x - 2

= 10x⁴ + 4x³ - 15x² - 11x - 2

\(\left(2x^3-3x-1\right)\left(5x+2\right)\\ =10x^4-15x^2-5x+4x^3-6x-2\\ =10x^4+4x^3-15x^2-11x-2\)

\(\left(x+1\right)\left(x^2-x+1\right)\\ =x^3+1^3\\ =x^3+1\)

\(\left(x+3\right)\left(x^2+3x-5\right)\\ =x^3+3x^2-5x+3x^2+9x-15\\ =x^3+6x^2+4x-15\)

   (x + 3) . ( x² + 3x - 5)

= x³ + 3x² - 5x + 3x² + 9x - 15

= x³ + 6x² + 4x - 15

\(\left(2x-1\right)\left(3x+2\right)\left(3-x\right)\\ =\left(6x^2+x-2\right)\left(3-x\right)\\ =18x^2+3x-6-6x^3-x^2+2x\\ =-6x^3+17x^2+5x-6\)

   (2x - 1) . (3x + 2) . (3 - x)

= (6x² + 4x - 3x - 2) . (3 - x)

= 18x² + 12x - 9x - 6 - 6x³ - 4x² + 3x² + 2x

= -6x³ + 17x² + 5x - 6

M = (1 - x)² . (1 + 2x) + (1 + x)² . (1 - 2x) - 6 . (1 - x) . (1 + x)

M = (1² - 2.1.x + x²) . (1 + 2x) + (1² + 2.1.x + x²) . (1 - 2x) - 6 .(1² -x²)

M = 1 - 2x + x² + 2x - 4x² + 2x³ + 1 + 2x + x² - 2x - 4x² - 2x³ - (6-6x²)

M = 1 - 2x + x² + 2x - 4x² + 2x³ + 1 + 2x + x² - 2x - 4x² - 2x³ - 6+ 6x²

M = - 4

vậy giá trị biểu thức trên không phụ thuộc vào x

1. He gets people to make all his shoes in Italy.
  He has all his shoes made in Italy ……………………………………...
2. Philip isn't here - someone is cutting his hair for him.
  Philip isn't here – He …is having his hair cut…………………………………...
3. We got some people to build our garage last year.
  We .……had our garage built last year ………………………………..
4. We have just paid someone to paint our house.
  We .…have just had our house painted…………………………………..
5. When are you going to pay someone to develop those photos?
  When are you going to have those photos …developed………………………………….. ?
6. I'll have to go to the optician's and tell him to change my glasses.
  I'll have to go to the optician's to have my glasses changed .
7. Sean went to the local bicycle repair shop for fixing the rear wheel of his bike.
  Sean went to the local bicycle repair shop .…to have the rear wheel of his bike fixed…………………………………..
8. Helen's car was dirty this morning, but it looks perfect now. She's been to the garage. [Present Perfect]
  Helen has had her car ……washed………………………………..at the garage.
9. Do you ask someone to type your essays?
  Do......you have your essays typed........................... ?
10. My granny Violet doesn't like asking people to do her shopping.
  My granny Violet doesn't like having people do her shopping.

Gọi \(n_{CuSO_4}=n_{CaCO_3}=a\left(mol\right)\)

`=> 160a + 100a = 52`

`=> a = 0,2 (mol) = n_{CuSO_4} + n_{CaCO_3}`

    (12 x \(\dfrac{27}{9}\) + 15 ) - 2 x (9 + 8²)

=  (12 x 3 + 15) - 2 x ( 9 + 64)

= ( 36 + 15) - 2 x 73

= 51 - 146

= -95 

 ( 12 x $\genfrac{}{}{0ex}{}{27}{9}$ + 15 ) - 2 x ( 9 + 82 )

=  ( 12 x 3 + 15 ) - 2 x ( 9 + 64 )

= ( 36 + 15 ) - 2 x 73

= 51 - 146

= - 95 

Thu gọn

\(B=2m^6+3m^3n^3+n^6+n^3\)

\(=2m^6+2m^3n^3+m^3n^3+n^6+n^3\)

\(=2m^3(m^3+n^3)+n^3(m^3+n^3)+n^3\)

Thay \(m^3+n^3=1\)vào biểu thứ B ta có:

\(B=2m^3.1+n^3.1+n^3=2\left(m^3+n^3\right)=2.1=2\)

Đs