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a) Ta có: \(a^3y^3+125\)
\(=\left(ay+5\right)\left(a^2y^2-5ay+25\right)\)
b) Ta có: \(8x^3-y^3-6xy\cdot\left(2x-y\right)\)
\(=\left(2x-y\right)\left(4x^2+2xy+y^2\right)-6xy\left(2x-y\right)\)
\(=\left(2x-y\right)\left(4x^2+2xy-6xy+y^2\right)\)
\(=\left(2x-y\right)^3\)
Lời giải:
$x^4y^4-z^4=(x^2y^2)^2-(z^2)^2=(x^2y^2-z^2)(x^2y^2+z^2)$
$=(xy-z)(xy+z)(x^2y^2+z^2)$
$(x+y+z)^2-4z^2=(x+y+z)^2-(2z)^2=(x+y+z-2z)(x+y+z+2z)$
$=(x+y-z)(x+y+3z)$
$\frac{-1}{9}x^2+\frac{1}{3}xy-\frac{1}{4}y^2=\frac{-4x^2+12xy-9y^2}{36}$
$=-\frac{4x^2-12xy+9y^2}{36}=-\frac{(2x-3y)^2}{36}=-\left(\frac{2x-3y}{6}\right)^2$
(2x+1)^2-(x-1)^2
= (4x^2 + 4x +1) - (x^2 - 2x +1)
= 2x^2 + 6x
= 2x(x+3)
9(x+5)^2-(x-7)^2
= 9 (x^2 + 10x + 25) - (x^2 - 14x +49)
= 9x^2 + 90x + 225 - x^2 + 14x - 49
= 8x^2 + 104x + 176
= 8x^2 + 8 * 13x + 8 * 22
= 8(x^2 + 13x +22)
x^2-y^2-x+y
= (x^2 - y^2) - (x-y)
= (x-y) (x+y) - (x-y)
= (x-y) (x+y+1)
a) (x-1)(2x+5)
b) (x+1)(x-5)
c) [(x+1)^2](x^2+x+1)
d) (x-1)(x^3-x-1)
e) (x+y)(x-y-1)
a) 2x2 + 3x - 5 = 2x2 + 5x - 2x - 5 = x(2x + 5) - (2x + 5) = (x - 1)(2x + 5)
b) x2 - 4x - 5 = x2 - 5x + x - 5 = x(x - 5) + (x - 5) = (x + 1)(x - 5)
c) x4 + x3 + x + 1 = x3(x + 1) + (x + 1) = (x + 1)(x3 + 1) = (x + 1)2(x2 - x + 1)
d) x4 - x3 - x2 + 1 = x3(x - 1) - (x - 1)(x + 1) = (x - 1)(x3 - x - 1)
e) -x - y2 + x2 - y = -(x + y) + (x - y)(x + y) = (-1 + x - y)(x + y)
a) \(a^3+a^2b-a^2c-abc=a^2\left(a+b\right)-ac\left(a+b\right)=a\left(a+b\right)\left(a-c\right)\)
b) mk chỉnh lại đề
\(x^2+2xy+y^2-xz-yz=\left(x+y\right)^2-z\left(x+y\right)=\left(x+y\right)\left(x+y-z\right)\)
c) \(4-x^2-2xy-y^2=4-\left(x+y\right)^2=\left(2-x-y\right)\left(2+x+y\right)\)
d) \(x^2-2xy+y^2-z^2=\left(x-y\right)^2-z^2=\left(x-y-z\right)\left(x-y+z\right)\)
\(3x\cdot\left(x-y\right)^2-6\cdot\left(y-x\right)\)
\(=3x\left(x-y\right)^2+6\left(x-y\right)\)
\(=\left(x-y\right)\left[3x\left(x-y\right)+6\right]\)
\(=\left(x-y\right)\left(3x^2-3xy+6\right)\)
a) ( 3x - 1 )2 - 4
= ( 3x - 1 ) - 22
= ( 3x - 1 - 2 )( 3x - 1 + 2 )
= ( 3x - 3 )( 3x + 1 )
= 3( x - 1 )( 3x + 1 )
b) ( x + y )2 - x2
= ( x + y - x )( x + y + x )
= y( 2x + y )
c) 100 - ( 2x - y )2
= 102 - ( 2x - y )2
= [ 10 - ( 2x - y ) ][ 10 + ( 2x - y ) ]
= ( 10 - 2x + y )( 10 + 2x - y )
d) ( 2x - 1 )2 - ( x - 1 )2
= [ ( 2x - 1 ) - ( x - 1 ) ][ ( 2x - 1 ) + ( x - 1 ) ]
= ( 2x - 1 - x + 1 )( 2x - 1 + x - 1 )
= x( 3x - 2 )
e) 4( x + 6 )2 - 9( 1 + x )2
= 22( x + 6 )2 - 32( 1 + x )2
= ( 2x + 12 )2 - ( 3 + 3x )2
= [ ( 2x + 12 ) - ( 3 + 3x ) ][ ( 2x + 12 + ( 3 + 3x ) ]
= ( 2x + 12 - 3 - 3x )( 2x + 12 + 3 + 3x )
= ( 9 - x )( 5x + 15 )
= 5( 9 - x )( x + 3 )