(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

    (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

`(3x-5)(7-5x)-(5x+2x)(2-3x)=4`

`<=>21x-15x^{2}-35+25x-7x(2-3x)=4`

`<=>-15x^{2}+46x-35-14x+21x^{2}=4`

`<=>6x^{2}+32x-39=0`

`<=>x^{2}+(16)/(3)x-(13)/(2)=0`

`<=>(x+(8)/(3))^{2}=245/18`

`=>x+(8)/(3)=+-(7\sqrt{10})/(6)`

`=>x=(-16+-7\sqrt{10})/(6)`