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bài 1:
a) x(x-2)-5y-(x-2)=(x-5y)(x-2)
b) =(2x-3-4x)(2x-3+4x)=(-2x-3)(6x-3)
bài 2 bạn tự luyện nhé
\(2x^3y-2xy^3-4xy^2-2xy\)
\(=2xy.\left(x^2-y^2-2y-1\right)\)
\(=2xy.[x^2-\left(y^2+2y+1\right)]\)
\(=2xy.[x^2-\left(y+1\right)^2]\)
\(=2xy.\left(x+y+1\right).\left(x-y-1\right)\)
Vậy chọn đáp án A
a) \(6\text{x}\left(x-y\right)-3\left(x-y\right)^2\)
\(=\left(x-y\right)\left(6\text{x}-3\text{x}+3y\right)\)
\(=\left(x-y\right)\left(3\text{x}+3y\right)\)
\(=3\left(x-y\right)\left(x+y\right)\)
\(=3\left(x^2-y^2\right)\)
b) \(2\text{a}\left(x-1\right)+b\left(x-1\right)-\left(1-x\right)\)
\(=2\text{a}\left(x-1\right)+b\left(x-1\right)+\left(x-1\right)\)
\(=\left(x-1\right)\left(2\text{a}+b+1\right)\)
c) \(2\text{x}\left(x-2\right)-\left(x-2\right)^2+5\text{x}\left(2-x\right)\)
\(=2\text{x}\left(x-2\right)-\left(x-2\right)^2-5\text{x}\left(x-2\right)\)
\(=\left(x-2\right)\left(2\text{x}-x+2-5\text{x}\right)\)
\(=\left(x-2\right)\left(2-4\text{x}\right)\)
a) \(6x\left(x-y\right)-3\left(x-y\right)^2\)
\(=3\left(x-y\right)\left(2x-x+y\right)\)
b) \(2a\left(x-1\right)+b\left(x-1\right)-\left(1-x\right)\)
\(=2a\left(x-1\right)+b\left(x-1\right)+\left(x-1\right)\)
\(=\left(x-1\right)\left(2a+b+1\right)\)
c) \(2x\left(x-2\right)-\left(x-2\right)^2+5x\left(2-x\right)\)
\(=2x\left(x-2\right)-\left(x-2\right)^2-5x\left(x-2\right)\)
\(=\left(x-2\right)\left(2x-x+2-5x\right)\)
\(=\left(x-2\right)\left(-4x+2\right)\)
\(1.=\left(2-3a-3+a\right)\left(2-3a+3-a\right)\)
\(=\left(-1-2a\right)\left(5-4a\right)\)
\(2.=x\left(x^2-1\right)+2\left(x^2-1\right)\)
\(=\left(x+2\right)\left(x-1\right)\left(x+1\right)\)
bạn hãy dùng máy tính tìm nghiệm là đc bạn nhé ! như vậy sẽ nhanh hơn !
x2( x + 1 )2 + 2x2 + 2x - 8
= [ x( x + 1 ) ]2 + 2( x2 + x ) - 8
= ( x2 + x )2 + 2( x2 + x ) - 8 (*)
Đặt a = x2 + x
(*) = a2 + 2a - 8
= a2 - 2a + 4a - 8
= a( a - 2 ) + 4( a - 2 )
= ( a - 2 )( a + 4 )
= ( x2 + x - 2 )( x2 + x + 4 )
= ( x2 - x + 2x - 2 )( x2 + x + 4 )
= [ x( x - 1 ) + 2( x - 1 ) ]( x2 + x + 4 )
= ( x - 1 )( x + 2 )( x2 + x + 4 )
ta co
\(x^2\left(x+1\right)^2+2x^2+2x-8\)
=\(\left(x\left(x+1\right)\right)^2+2x\left(x+1\right)+1-9\)
=\(\left(x^2+x+1\right)^2-9\)
=\(\left(x^2+x-8\right)\left(x^2+x+10\right)\)
=\(\left(x^2+2x\frac{1}{2}+\frac{1}{4}-\frac{33}{4}\right)\left(x^2+x+10\right)\)
=\(\left(\left(x+\frac{1}{2}\right)^2-\frac{33}{4}\right)\left(x^2+x+10\right)\)
=\(\left(x+\frac{1}{2}-\sqrt{\frac{33}{4}}\right)\left(x+\frac{1}{2}+\sqrt{\frac{33}{4}}\right)\left(x^2+x+10\right)\)