a)  ( x + 1 ) ( x - 1 )

    = ( x² + 1 )

b) ( x - 2y ) ( x + 2y )

  = ( x² - 4y² )

c) 56 x 64 

  = ( 60 - 4 ) ( 60 + 4 )

  = 3 600 - 16

  = 3 584

a) = x² - 1

b) = x² - 4y²

Bài 3:

a: \(M=4x^2-20x+25\)

\(=\left(2x\right)^2-2\cdot2x\cdot5+5^2\)

\(=\left(2x-5\right)^2=\left(2\cdot\frac{105}{2}-5\right)^2=\left(105-5\right)^2=100^2=10000\)

b: \(x^3-\frac19x=0\)

=>\(x\left(x^2-\frac19\right)=0\)

=>\(x\left(x-\frac13\right)\left(x+\frac13\right)=0\)

=>\(\left[\begin{array}{l}x=0\\ x-\frac13=0\\ x+\frac13=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=0\\ x=\frac13\\ x=-\frac13\end{array}\right.\)

Bài 2:

a: \(6x^3y-9x^2y^2=3x^2y\cdot2x-3x^2y\cdot3y\)

\(=3x^2y\left(2x-3y\right)\)

b: \(4x^2-25=\left(2x\right)^2-5^2=\left(2x-5\right)\left(2x+5\right)\)

Bài làm

Ta có: A = x² - 2y + xy + 1 ; B = x²y - x²y² - 1; C = - y - x²y² 

=> A + B - C = ( x² - 2y + xy + 1 ) + ( x²y - x²y² - 1 ) - ( - y - x²y² )

=> A + B - C = x² - 2y + xy + 1 + x²y - x²y² + y + x²y² 

=> A + B - C = x² + ( -2y + y ) + xy + ( -x²y² + x²y² ) + 1 + x²y 

=> A + B - C = x² - y + xy + 1 + x²y 

Vậy A + B - C = x² - y + xy + 1 + x²y 

# Học tốt #

Cho các đa thức: A= x^2- 2y +xy1; B=x^2 + y-x^2y^2-1; C=-y- x^2y^2. Tính A+B-C

#giúp mik làm bài kiểu này vs ạ

a: 2x+6=2x+x-2y=3x-2y

2y-6=2y-(x-2y)=2y-x+2y=4y-x

\(L=\frac{2x+6}{3x-2y}+\frac{2y-6}{4y-x}\)

=1+1

=2

b: x-y-z=0

=>x=y+z; x-z=y; y+z=x; x-y=z

Sửa đề: \(M=\left(1-\frac{z}{x}\right)\left(1-\frac{x}{y}\right)\left(1+\frac{y}{z}\right)\)

\(=\frac{x-z}{x}\cdot\frac{z+y}{z}\cdot\frac{y-x}{y}=\frac{y}{x}\cdot\frac{x}{z}\cdot\frac{-z}{y}=-1\)

b)(x-2y)(x+2y)

=x^2-4y^2

c)(x-1)(x^2+x+1)

=x^3-1

Giup mik vs

a/

\(2x\left(x+5\right)\left(x-1\right)\)

\(=\left(2x^2+10x\right)\left(x-1\right)\)

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

\(=2x^3+8x^2-10x\)

b/

\(\left(x-2y\right)\left(x+2y\right)\)

\(=x^2-\left(2y\right)^2\)

\(=x^2-4y^2\)

c/

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

\(=\left(x-1\right)\left(x^2+x\cdot1+1^2\right)\)

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

\(=x^3-1\)

a) Ta có: ( x - 2 )( x + 2 ) = ( x )² - 2² = x² - 4.

b) Ta có: 56.64 = ( 60 - 4 )( 60 + 4 ) = 60² - 4² = 3600 - 16 = 3584.