A=19;B=-50

A = 5 . ( - 3) .2 - 13 .( -3) + 5.2

A = - 30 + 39 + 10

A = 19

B = -2x + 16y - 15xy

B = (-2) . 2 + 16 .( - 1) - 15.2.(-1)

B = -4  - 16 + 30

B = 10 

A = 5 . ( -3 ) . 2 - 13 . ( -3 ) + 5 . 2                    B = -2 . 2 + 16 . ( -1 ) - 15 . 2 . ( -1 ) 

= ( -30 ) - ( -39 ) + 10                                       = -4 + ( -16 ) - ( -30 ) 

= -30 + 39 + 10                                               = ( -30 ) + 30

= 9 + 10                                                         = 0

= 19

a: Ta có: \(\left(x^2+x-1\right)^2-\left(x^2+2x+3\right)^2\)

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

\(=\left(-x-4\right)\left(2x^2+3x+2\right)\)

b: Ta có: \(\left(x-3\right)^2-16\)

\(=\left(x-3-4\right)\left(x-3+4\right)\)

\(=\left(x+1\right)\left(x-7\right)\)

c: \(y^2+16y+64=\left(y+8\right)^2\)

\(M=5.2.\left(-3\right)-10=3.\left(-3\right)\)

\(M=-30-10=-9\)

\(M=-40+9\)

\(M=-31\)

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

\(N=2.\left(1-1\right)+3.\left(-1\right)-2\)

\(N=-3-2\)

\(N=-5\)

Thay x= -1 vào biểu thức, ta được:

N= 2 .((-1)^2 -1) + 3.(-1) -2

   = 2.(1-1) +(-3)-2

   = 2.0 + (-3) -2

   = 0 +(-3) -2 

   = -5 

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

\(=\left(x-1\right)^3-y^3\)

\(=\left(x-1-y\right).\left[\left(x-1\right)^2+\left(x-1\right).y+y^2\right]\)

Đề là gì bạn nhỉ?

\(16-\left(x-3\right)^2=4^2-\left(x-3\right)^2=\left(4-x-3\right)\left(4+x-3\right)\)

\(64+16y+y^2=y^2+2y4+4^2=\left(y+4\right)^2\)

\(1,24^2-0,24^2=\left(1,24-0,24\right)\left(1,24+0,24\right)=1.1,48=1,48\)

\(\frac{1}{8}-8x^3=\left(\frac{1}{2}\right)^3-\left(2x\right)^3=\left(\frac{1}{2}-2x\right)\left(\frac{1}{4}+x+4x^2\right)\)

\(100-\left(3x-y\right)^2=10^2-\left(3x-y\right)=\left(10-3x+y\right)\left(10+3x-y\right)\)

\(64x^2-\left(8x+3\right)^2\)

\(=\left(8x\right)^2-\left(8x+3\right)^2\)

\(=\left(8x-8x-3\right)\left(8x+8x+3\right)\)

\(=\left(-3\right)\left(16x+3\right)\)

\(=-48x-9\)

xy³+4xy³-3xy³

=5xy³-3xy³ = 2xy³

tươg tự

Bài 2 : Thay zô có j kó đâu ==

Bài 1

( x - y )² - 4

= ( x - y )² - 2²

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

x² - 16( x + y )²

= x² - 4²( x + y )²

= x² - ( 4x + 4y )²

= ( x² - 4x - 4y )( x² - 4x + 4y )

8x³ + 36x²y + 54xy² + 27y³

= ( 2x )³ + 3.( 2x )².3y + 3.2x.( 3y )² + ( 3y )³

= ( 2x + 3y )³

Bài 2.

a) ( x² + 4 )( x² - 4 ) - ( x² + 1 )( x² - 1 )

= [ ( x² )² - 4² ] - [ ( x² )² - 1² ]

= x⁴ - 16 - x⁴ + 1

= -15

b) ( y - 3 )( y + 3 )( y² + 9 )( y² + 2 )( y² - 2 )

= [ ( y - 3 )( y + 3 )( y² + 9 ) ][ ( y² + 2 )( y² - 2 ) ]

= { [ ( y - 3 )( y + 3 ) ]( y² + 9 ) }[ ( y² )² - 2² ]

= [ ( y² - 9 )( y² + 9 ) ]( y⁴ - 4 )

= ( y⁴ - 81 )( y⁴ - 4 )

= y⁴( y⁴ - 4 ) - 81( y⁴ - 4 )

= y⁸ - 4y⁴ - 81y⁴ + 324

= y⁸ - 85y⁴ + 324