Phân tích thành nhân tử:
a) \(7x^2-7y^2-14x+14y\)
b) \(x^2+9x+20\)
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A) 7X2 - 7Y2 - 14X + 14Y
= ( 7X2 - 7Y2 ) - ( 14X - 14Y )
= 7( X2 - Y2 ) - 14( X - Y )
= 7( X - Y )( X + Y ) - 14( X - Y )
= 7( X - Y )( X + Y - 14 )
B) X2 - Y2 + 14X + 49
= ( X2 + 14X + 49 ) - Y2
= ( X + 7 )2 - Y2
= ( X - Y + 7 )( X + Y + 7 )
C) X2 - Y2 - X + Y
= ( X2 - Y2 ) - ( X - Y )
= ( X - Y )( X + Y ) - ( X - Y )
= ( X - Y )( X + Y - 1 )
D) X2 + 12Y - Y2 - 36
= X2 - ( Y2 - 12Y + 36 )
= X2 - ( Y - 6 )2
= ( X - Y + 6 )( X + Y - 6 )
E) X3 + X2 - 9X - 9
= ( X3 + X2 ) - ( 9X + 9 )
= X2( X + 1 ) - 9( X + 1 )
= ( X + 1 )( X2 - 9 )
= ( X + 1 )( X - 3 )( X + 3 )
Vô đây xem: bài 1:phân tích đa thức thành nhân tửa)7x^3y-14x^2y+7xy^3b)3x^2-3xy-5x+5yc)x^2+7x+12giúp mình với - Hoc24
`a)7x^3y^2+14x^2y^3+7xy^4`
`=7xy^2(x^2+2xy+y^2)`
`=7xy^2(x+y)^2`
______________________________________________
`b)x^2-xy+5x-5y`
`=x(x-y)+5(x-y)`
`=(x-y)(x+5)`
______________________________________________
`c)3x^2-6xy-12+3y^2`
`=3(x^2-2xy-4+y^2)`
`=3[(x-y)^2-4]`
`=3(x-y-2)(x-y+2)`
a)7x3y2+14x2y3+7xy4
=7xy2(x2+2xy+y2)
=7xy2(x+y)2
b)x2-xy + 5x - 5y
=x(x-y) + 5(x-y)
=(x-y) (x+5)
thiếu đăng lại.
Phân tích các đa thức sau thành nhân tử:
a,5x2 - 5xy + 7y - 7x ;
b,x2 + 2xy + x + 2y ;
c,x2 - 6x - 9y2 + 9 ;
a: =5x(x-y)-7(x-y)
=(x-y)(5x-7)
b: =x(x+2y)+(x+2y)
=(x+2y)(x+1)
c; =(x-3)^2-9y^2
=(x-3-3y)(x-3+3y)
a
\(5x^2-5xy+7y-7x\\ =5x\left(x-y\right)+7\left(y-x\right)\\ =5x\left(x-y\right)-7\left(x-y\right)\\ =\left(5x-7\right)\left(x-y\right)\)
b
\(x^2+2xy+x+2y\\ =x\left(x+2y\right)+\left(x+2y\right)\\ =\left(x+1\right)\left(x+2y\right)\)
c
\(x^2-6x-9y^2+9\\ =x^2-6x+9-\left(3y\right)^2\\ =x^2-2.x.3+3^2-\left(3y\right)^2\\ =\left(x-3\right)^2-\left(3y\right)^2\\ =\left(x-3-3y\right)\left(x-3+3y\right)\)
`@` `\text {Ans}`
`\downarrow`
`x^2 - 8xy + 7y^2`
`= x^2 - xy - 7xy + 7y^2`
`= (x^2 - xy) - (7xy - 7y^2)`
`= x(x - y) - 7y(x - y)`
`= (x - 7y)(x - y)`
___
`x^2 - 9xy + 14y^2`
`= x^2 - 2xy - 7xy + 14y^2`
`= (x^2 - 2xy) - (7xy - 14y^2)`
`= x(x - 2y) - 7y(x - 2y)`
`= (x - 7y)(x - 2y)`
___
`x^2 - 11xy + 18y^2`
`= x^2 - 2xy - 9xy + 18y^2`
`= (x^2 - 2xy) - (9xy - 18y^2)`
`= x(x - 2y) - 9y(x - 2y)`
`= (x - 9y)(x - 2y)`
a: =x^2-xy-7xy+7y^2
=x(x-y)-7y(x-y)
=(x-y)(x-7y)
b: =x^2-2xy-7xy+14y^2
=x(x-2y)-7y(x-2y)
=(x-2y)(x-7y)
c: =x^2-2xy-9xy+18y^2
=x(x-2y)-9y(x-2y)
=(x-2y)(x-9y)
b) x2 + 9x + 20 = x2 + 4x + 5x +20 =x(x + 4) + 5(x + 4) = (x + 4)(x+ 5)
a) 7x^2-7y^2-14x+14y= 7 ( x^2 - y^2 ) - 14 ( x+y) = 14 ( 2(x^2) - 2 (x^2))- 28 ( 2x+2y)
= 28 ( 4 ( x^2)-4(y^2))- 28 ( 2x+2y)
= 28 (4(x^2-y^2) - 4(x+y)
= 28 (4( x^2-y^2-x+y ))
= 112 . ( x-y-x+y)