c)\(4\left(x+1\right)\left(x+5\right)-\left(x+2\right)\left(x+5\right)-3\left(x+1\right)\left(x+2\right)\)

=\(4x^2+20x-4x-20-x^2-5x-2x-10-3x^2-6x+3x+6\)

\(=6x-30\).

Nếu thấy hay thì tick đúng cho m nha bạn

a)\(2x^2+3\left(x-1\right)\left(x+1\right)-5x\left(x+1\right)\)

\(=2x^2+3x^2-3-5x^2-5x\)

\(=-3-5x\).

b)\(\left(8-5x\right)\left(x+2\right)+4\left(x-2\right)\left(x+1\right)+2\left(x-2\right)\left(x+2\right)+10\)

\(=8x+16-5x^2-10x+4x^2-4x-8+2x^2-8+10\)

\(=3x^2-6x+10\).

Đặt 123456=x và 987654=y. Theo bài ra , ta có:

-A= x(x+1)-(x-1)(x+2)=(x\(^2\)+x)-(x\(^2\)+2x-x-2)=x\(^2\)+x-x\(^2\)-2x+x+2=2.

-B=y(y+1)-(y-1)(x+2)=(y\(^2\)+y)-(y\(^2\)+2y-y-2)=y\(^2\)+y-y\(^2\)-2y+y+2=2.

\(\Rightarrow\)A=B.

Thấy đúng thì tick cho m nha

c)(x+y+z)² = [(x + y) + z]² = (x + y)² + 2(x + y)z + z²

= x²+ 2xy + y² + 2xz + 2yz + z²

= x² + y² + z² + 2xy + 2yz + 2xz

a) (x²y² – xy + 2y)(x – 2y)

= x²y². X + x²y²(-2y) + (xy) . x + (-xy)(-2y) + 2y . x + 2y(-2y)

= x³y² – 2x²y³- x²y + xy² + 2xy – 4y²

b) (x² – xy + y²)(x + y) = x² . x + x². y + (-xy) . x + (-xy) . y + y² . x + y². y

= x³ + x². y - x². y - xy² + xy² + y³

= x³ - y³

Tick đúng nha bạn

a) (x² – 2x+ 1)(x – 1)

= x² . x + x².(-1) + (-2x). x + (-2x). (-1) + 1 . x + 1 . (-1)

= x³ - x² - 2x² + 2x + x – 1

= x³ - 3x² + 3x – 1

b) (x³ – 2x² + x -1)(5 – x)

= x³ . 5 + x³ . (-x) + (-2 x²) . 5 + (-2x²)(-x) + x . 5 + x(-x) + (-1) . 5 + (-1) . (-x)

= 5 x³ – x⁴ – 10x² + 2x³ +5x – x² – 5 + x

= - x⁴ + 7x³ – 11x²+ 6x - 5.

Suy ra kết quả của phép nhan:

(x³ – 2x² + x -1)(x - 5) = (x³ – 2x² + x -1)(-(5 - x))

= - (x³ – 2x² + x -1)(5 – x)

= - (- x⁴ + 7x³ – 11x²+ 6x -5)

= x⁴ - 7x³ + 11x²- 6x + 5

a) \(\left(x-1\right)\left(x^2+x+1\right)\)

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

\(\RightarrowĐPCM\)

b)\(\left(x^3+x^2y+xy^2+y^3\right)\left(x-y\right)\)

\(=x^4-x^3y+x^3y-x^2y^2+x^2y^2-xy^3+xy^3-y^4=x^4-y^4\)

tick đúng nha bạn

c)\(4\left(6-x\right)+x^2\left(2+3x\right)-x\left(5x-4\right)+3x^2\left(1-x\right)\)

=\(24-4x+2x^2+3x^3-5x^2+4x+3x^2-3x^3=24\)

Vậy gtbt trên ko phụ thuộc vào gt của biến.