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Ik mk nha, hôm nay ngày mai, ngày kia mk ik 3 lần lại cho bạn (thành 9 lần)
Nhớ kb với mìn lun nha!! Mk rất vui đc làm quen vs bạn, cảm ơn mn nhìu lắm
a) 4x2 - 20x + 25 - 36y2
= (2x - 5)2 - 36y2
= (2x - 5 - 6y)(2x - 5 + 6y)
b) x3 + x2 - 2x - 8
= (x3 - 8) + (x2 - 2x)
= (x - 2)(x2 + 2x + 4) + x(x - 2)
= (x - 2)(x2 + 2x + 4 + x)
= (x - 2)(x2 + 3x + 4)
d) x4 + 6x3 + 9x2 - 16
= x2(x2 + 6x + 9) - 16
= x2(x + 3)2 - 16
= (x2 + 3x)2 - 16
= (x2 + 3x - 4)(x2 + 3x + 4)
= (x2 + 4x - x - 4)(x2 + 3x + 4)
= [x(x + 4) - (x + 4)](x2 + 3x + 4)
= (x - 1)(x + 4)(x2 + 3x + 4)
a ) x3 + 2x - 3
= x3 - x2 + x2 - x + 3x - 3
= x2. ( x - 1 ) + x ( x - 1 ) + 3 . ( x - 1 )
= ( x - 1 ) ( x2 + x + 3 )
b ) x3 - 7x + 6
= x3 - x2 + x2 - x - 6x + 6
= x2 ( x - 1 ) + x ( x - 1 ) - 6 .( x - 1 )
= ( x - 1 ) ( x2 + x - 6 )
= ( x - 1 ) ( x2 - 2x + 3x - 6 )
= ( x - 1 ) [ x ( x - 2 ) + 3. ( x - 2 ) ]
= ( x - 1 ) ( x - 2 ) . ( x + 3 )
c ) x3 + 5x2 + 8x + 4
= x3 + x2 + 4x2 + 4x + 4x + 4
= x2 ( x + 1 ) + 4x ( x + 1 ) + 4 ( x + 1 )
= ( x + 1 ) . ( x2 + 4x + 4 )
= ( x + 1 ) . ( x + 2 )2
d ) x3 - 9x2 + 6x + 16
= x3 + x2 - 10x2 - 10x + 16x + 16
= x2 ( x + 1 ) - 10x ( x + 1 ) + 16 ( x + 1 )
= ( x + 1 ) ( x2 - 10x + 16 )
= ( x + 1 ) ( x2 - 2x - 8x + 16 )
= ( x + 1 ) . [ x. ( x - 2 ) - 8 . ( x - 2 ) ]
= ( x + 1 ) . ( x - 2 ) . ( x - 8 )
e ) x3 - x2 - x - 2
= x3 - 2x2 + x2 - 2x + x - 2
= x2 ( x - 2 ) + x ( x - 2 ) + ( x - 2 )
= ( x - 2 ) ( x2 + x + 1 )
g ) x3 + x2 - x + 2
= x3 + 2x2 - x2 - 2x + x + 2
= x2 ( x + 2 ) - x ( x + 2 ) + ( x + 2 )
= ( x + 2 ) ( x2 - x + 1 )
h ) x3 - 6x2 - x + 30
= x3 + 2x2 - 8x2 - 16x + 15x + 30
= x2 ( x + 2 ) - 8x ( x + 2 ) + 15 ( x + 2 )
= ( x + 2 ) ( x2 - 8x + 15 )
= ( x + 2 ) ( x2 - 5x - 3x + 15 )
= ( x + 2 ) [ x ( x - 5 ) - 3 ( x - 5 ) ]
= ( x + 2 ) ( x - 5 ) ( x - 3 )
a ) x3 + 2x - 3
= x3 - x2 + x2 - x + 3x - 3
= x2. ( x - 1 ) + x ( x - 1 ) + 3 . ( x - 1 )
= ( x - 1 ) ( x2 + x + 3 )
b ) x3 - 7x + 6
= x3 - x2 + x2 - x - 6x + 6
= x2 ( x - 1 ) + x ( x - 1 ) - 6 .( x - 1 )
= ( x - 1 ) ( x2 + x - 6 )
= ( x - 1 ) ( x2 - 2x + 3x - 6 )
= ( x - 1 ) [ x ( x - 2 ) + 3. ( x - 2 ) ]
= ( x - 1 ) ( x - 2 ) . ( x + 3 )
P/s tham khảo nha
x4 + x3 + 6x2 + 5x + 5
=x4+x3+x2+5x2+5x+5
=x2.(x2+x+1)+5.(x2+x+1)
=(x2+x+1)(x2+5)
a) bt \(=\left(x-8\right)\left(x^2-x-2\right)=\left(x-8\right)\left(x+1\right)\left(x-2\right)\)
kl: ...
b) \(=\left(x+2\right)\left(x^2-8x-15\right)=\left(x+2\right)\left(x-5\right)\left(x-3\right)\)
kl:....
a, \(x^3-9x^2+6x+16\)
\(=x^3-8x^2-x^2+8x-2x+16\)
\(=x^2\left(x-8\right)-x\left(x-8\right)-2\left(x-8\right)\)
\(=\left(x-8\right)\left(x^2-x-2\right)\)
\(=\left(x-8\right)\left(x^2-2x+x-2\right)\)
\(=\left(x-8\right)\left[x\left(x-2\right)+\left(x-2\right)\right]\)
\(=\left(x-8\right)\left(x-2\right)\left(x+1\right)\)
b, \(x^3-6x^2-x+30\)
\(=x^3-5x^2-x^2+5x-6x+30\)
\(=x^2\left(x-5\right)-x\left(x-5\right)-6\left(x-5\right)\)
\(=\left(x-5\right)\left(x^2-x-6\right)\)
\(=\left(x-5\right)\left(x^2-3x+2x-6\right)\)
\(=\left(x-5\right)\left[x\left(x-3\right)+2\left(x-3\right)\right]\)
\(=\left(x-5\right)\left(x-3\right)\left(x+2\right)\)
Chúc bạn học tốt!!!