Toán Lớp 8: Phân tích đa thức thành nhân tử
1.27xy-18x²y+3x³y
2.2x³-8
3.9x²-(x-1)²
4.x²-3x+6y-4y²
5.x²-2(x-3)²-9
6.x⁴-2x³-x+2
7.x²-2x-8
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Toán Lớp 8: Phân tích đa thức thành nhân tử
1.27xy-18x²y+3x³y
2.2x³-8
3.9x²-(x-1)²
4.x²-3x+6y-4y²
5.x²-2(x-3)²-9
6.x⁴-2x³-x+2
7.x²-2x-8
Comments ( 1 )
a) 27xy -18xᒾy +3x³y
= 3xy (9 -6x +xᒾ )
= 3xy ( 3-x)ᒾ
= 3xy ( 3-x ) (3-x )
b) 2x³ -8
= 2 ( x³ -4 )
c) 9xᒾ – (x-1 )ᒾ
= ( 3x -x +1) (3x +x -1 )
= ( 2x +1 ) ( 4x -1 )
d) xᒾ -3x +6y – 4yᒾ
= ( xᒾ – 4yᒾ )-( 3x -6y )
= ( x – 2y ) ( x+2y ) – 3( x- 2y)
= ( x -2y ) ( x+2y -3)
e) xᒾ -2( x-3 )ᒾ -9
= ( xᒾ -9 ) – 2(x -3)ᒾ
= ( x-3) (x+3) -2(x-3) ( x-3)
= ( x-3)( x+3 -2x +6 )
= ( x-3)(9-x)
g) x⁴ -2x³ -x +2
= ( x⁴ -x)-(2x³-2)
= x(x³ -1)-2(x³-1)
= ( x-2)(x³ -1)
h) xᒾ -2x -8
= xᒾ +2x -4x -8
= x( x+2) – 4( x+2)
= ( x-4)(x+2)