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a) a3 - a2c + a2b - abc
= a( a2 - ac + ab - bc )
= a[ a( a - c ) + b( a - c ) ]
= a( a - c )( a + b )
b) ( x2 + 1 )2 - 4x2
= ( x2 + 1 )2 - ( 2x )2
= ( x2 - 2x + 1 )( x2 + 2x + 1 )
= ( x - 1 )2( x + 1 )2
c) x2 - 10x - 9y2 + 25
= ( x2 - 10x + 25 ) - 9y2
= ( x - 5 )2 - ( 3y )2
= ( x - 3y - 5 )( x + 3y - 5 )
d) 4x2 - 36x + 56
= 4( x2 - 9x + 14 )
= 4( x2 - 7x - 2x + 14 )
= 4[ x( x - 7 ) - 2( x - 7 ) ]
= 4( x - 7 )( x - 2 )
a,\(a^3-a^2c+a^2b-abc\)
\(=a\left(a^2-ac+ab-bc\right)\)
\(=a\left[a\left(a-c\right)+b\left(a-c\right)\right]\)
\(=a\left(a-b\right)\left(a-c\right)\)
b,\(\left(x^2+1\right)^2-4x^2\)
\(=\left(x^2+1-2x\right)\left(x^2+1+2x\right)\)
\(=\left(x-1\right)^2\left(x+1\right)^2\)
c,\(x^2-10x-9y^2+25\)
\(=\left(x^2-10x+25\right)-9y^2\)
\(=\left(x-5\right)^2-\left(3y\right)^2\)
\(=\left(x-5-3y\right)\left(x-5+3y\right)\)
d,\(4x^2-36x+56\)
\(=4\left(x^2-9x+14\right)\)
\(=4\left(x^2-7x-2x+14\right)\)
\(=4\left(x-7\right)\left(x-2\right)\)
Bài 1: (2 điểm) Phân tích các đa thức sau thành nhân tử
a) a3 – a2c + a2b – abc
= a(a2 - ac + ab - bc)
= a[a(a - c) + b(a - c)]
= a(a - c)(a + b)
b) (x2 + 1)2 – 4x2
= (x2 + 1)2 – (2x)2
= (x2 + 1 - 2x)(x2 + 1 + 2x)
= (x - 1)2. (x + 1)2
c) x2 – 10x – 9y2 + 25
= (x2 - 10x + 25) - 9y2
= (x - 5)2 - (3y)2
= (x - 5 + 3y)(x - 5 - 3y)
d) 4x2 – 36x + 56
= 4x2 - 28x - 8x + 56
= (4x2 - 28x) - (8x - 56)
= 4x(x - 7) - 8(x - 7)
= (x - 7)(4x - 8)
= 4(x - 7)(x - 2)
a) \(12xy-4x^2-9y^2=-\left(4x^2-12xy+9y^2\right)\)
= \(-\left(2x-3y\right)^2\)
b) \(10x-x^2-25=-\left(x^2-10x+25\right)=-\left(x-5\right)^2\)
c) \(x^4+4-4x^2\)
= \(\left(x^2-2\right)^2\)
`#040911`
`a)`
`196 - a^2 + 2ab - b^2`
`= 196 - (a^2 - 2ab + b^2)`
`= 196 - (a - b)^2`
`= 14^2 - (a - b)^2`
`= (14 - a + b)(14 + a - b)`
`b)`
`a^2 + 6a - 4b^2 + 9`
`= (a^2 + 6a + 9) - 4b^2`
`= [ (a)^2 + 2*a*3 + 3^2] - (2b)^2`
`= (a + 3)^2 - (2b)^2`
`= (a + 3 - 2b)(a + 3 + 2b)`
`c)`
`4x - 4 + 9y^2 - x^2`
`= 9y^2 - (x^2 - 4x + 4)`
`= (3y)^2 - [ (x)^2 - 2*x*2 + 2^2]`
`= (3y)^2 - (x - 2)^2`
`= (3y - x + 2)(3y + x - 2)`
`d)`
`5x^2 - 10x + 5 - 45t^2`
`= 5*(x^2 - 2x + 1 - 9t^2)`
`= 5*[ (x^2 - 2x + 1) - 9t^2]`
`= 5*{ [(x)^2 - 2*x*1 + 1^2] - (3t)^2}`
`= 5*[ (x - 1)^2 - (3t)^2]`
`= 5*(x - 1 - 3t)(x - 1 + 3t)`
`e)`
`x^2 - 36y^2t^2 - 10x +25`
`= (x^2 - 10x + 25) - 36y^2t^2`
`= [ (x)^2 - 2*x*5 + 5^2] - (6yt)^2`
`= (x - 5)^2 - (6yt)^2`
`= (x - 5 - 6yt)(x - 5 + 6yt)`
a: =196-(a^2-2ab+b^2)
=196-(a-b)^2
=(14-a+b)(14+a-b)
b: \(=\left(a^2+6a+9\right)-4b^2\)
\(=\left(a+3\right)^2-4b^2\)
\(=\left(a+3-2b\right)\left(a+3+2b\right)\)
c: \(=9y^2-\left(x^2-4x+4\right)\)
\(=\left(3y\right)^2-\left(x-2\right)^2\)
\(=\left(3y-x+2\right)\left(3y+x-2\right)\)
d: \(=5\left(x^2-2x+1-9t^2\right)\)
\(=5\left[\left(x-1\right)^2-\left(3t\right)^2\right]\)
\(=5\left(x-1-3t\right)\cdot\left(x-1+3t\right)\)
e: \(=x^2-10x+25-36y^2t^2\)
\(=\left(x-5\right)^2-\left(6yt\right)^2\)
\(=\left(x-5-6yt\right)\left(x-5+6yt\right)\)
b: Ta có: \(B=x^2+4x+9y^2-6y-1\)
\(=x^2+4x+4+9y^2-6y+1-6\)
\(=\left(x+2\right)^2+\left(3y-1\right)^2-6\ge-6\forall x,y\)
Dấu '=' xảy ra khi x=-2 và \(y=\dfrac{1}{3}\)
mình chỉ phân tích thôi
a) 6x(4-x)+x-4
=6x(4-x)-(4-x)
=(6x-1)(4-x)
c) 25x^2-10x+1-16z^2
=(5x-1)^2-16z^2
=(5x-1-4z)(5x-1+4z)
ban xem lại đề bài câu b đi chắc là sai đó
còn các câu trên bạn tự làm nhé
Thực hiện phép tính:
a) (2x-3y)(4x2+6xy+9y2)
=8x3-27y3
b) (6x3+3x2+4x+2):(3x2+2)
=(3x2+2)(2x+1):(3x2+2)
=2x+1
c) (x+2)2+(3-x)-2(x+3)(x-3)
=x2+4x+4+3-x-2x2+18
=-x2+4x+25
Bài 2:
a: 6x(4-x)+(x-4)
=6x(4-x)-(4-x)
=(4-x)(6x-1)
b: \(=x^2-1+y\left(x^2-1\right)\)
\(=\left(x^2-1\right)\left(1+y\right)=\left(y+1\right)\left(x+1\right)\left(x-1\right)\)
c: \(=\left(5x-1\right)^2-\left(4z\right)^2\)
=(5x-1-4z)(5x-1+4z)
<3 U love you
a) a3 - a2c + a2b - abc
= a( a2 - ac + ab - bc )
= a[ ( a2 + ab ) - ( ac + bc ) ]
= a( a( a + b ) - c( a + b ) ]
= a( a + b )( a - c )
b) ( x2 + 1 )2 - 4x2
= ( x2 + 1 )2 - ( 2x )2
= ( x2 - 2x + 1 )( x2 + 2x + 1 )
= ( x - 1 )2( x + 1 )2
c) x2 - 10x - 9y2 + 25
= ( x2 - 10x + 25 ) - 9y2
= ( x - 5 )2 - ( 3y )2
= ( x - 3y - 5 )( x + 3y - 5 )
d) 4x2 - 36x + 56
= 4x2 - 8x - 28x + 56
= 4x( x - 2 ) - 28( x - 2 )
= 4( x - 2 )( x - 7 )