a, \(x^2-5x+6=x^2+x-6x+6=x\left(x-1\right)-6\left(x-1\right)=\left(x-1\right)\left(x-6\right)\)

b, \(3x^2+9x-30=3\left(x^2+3x-10\right)=3\left(x^2-2x+5x-10\right)\)

\(=3\left[x\left(x-2\right)+5\left(x-2\right)\right]=3\left(x-2\right)\left(x+5\right)\)

c, \(x^2+7x+10=x^2+2x+5x+10=x\left(x+2\right)+5\left(x+2\right)=\left(x+2\right)\left(x+5\right)\)

a) x² - 5x + 6 = (x²-2x)-(3x-6)=x(x-2)-3(x-2)=(x-3)(x-2)

b) 3x² + 9x -30= 3(x²+3x-10) = 3((x²+5x)-(2x+10)) = 3(x(x+5)-2(x+5)) = 3(x-2)(x+5)

c) x² + 7x + 10 =( x²+5x)+(2x+10)=x(x+5)+2(x+5)=(x+2)(x+5)

a, \(x^2-5x+6=\left(x-2\right)\left(x-3\right)\)

b, \(3x^2+9x-30=3\left(x^2+3x-10\right)\)

\(=\left(x+5\right)\left(x-2\right)\)

c, \(x^2+7x+10=\left(x+2\right)\left(x+5\right)\)

a/ \(\left(x+y\right)^2-8\left(x+y\right)+12\)

\(=\left(x+y\right)\left(x+y-8+12\right)\)

\(=\left(x+y\right)\left(x+y+4\right)\)

==========

b/\(\left(x^2+2x\right)^2-2x^2-4x-3\)

\(=\left(x^2+2x\right)^2-\left(2x^2+4x\right)-3\)

\(=\left(x^2+2x\right)^2-2\left(x^2+2x\right)-3\)

\(=\left(x^2+2x\right)\left(x^2+2x-5\right)\)

===========

c/ \(\left(x^2+x\right)^2-2\left(x^2+x\right)-15\)

\(=\left(x^2+x\right)\left(x^2+x-2-15\right)\)

\(=\left(x^2+x\right)\left(x^2+x-17\right)\)

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a) 7x – 14 = 7(x - 2)

b) 5x3 - 10x2y +5xy2 = 5x(x² - 2xy - y²) = 5x(x - y)²

c) 25 – x2= (x - 5)(x + 5)

a, \(7\left(x-2\right)\)

c, \(\left(5-x\right)\left(5+x\right)\)

 \(a,7x-14=7\left(x-2\right)\\ b.5x^3-10x^2y+5xy^2=5x\left(x^2-2xy+y^2\right)=5x\left(x-y\right)^2\\ c,25-x^2=\left(5-x\right)\left(5+x\right)\)

a, 7x - 14 = 7 ( x - 2 )

b, 5x³ - 10x²y + 5xy² 

= 5x ( x² - 2xy + y² ) 

= 5x ( x - y )²

c, 25 - x² = 5² - x² = ( 5 - x ) ( 5 + x )

\(A=x^2-y^2+7x+7y\)

\(=\left(x-y\right)\left(x+y\right)+7\left(x+y\right)\)

\(=\left(x+y\right)\left(x-y+7\right)\)

\(B=4x^3-4x^2+x\)

\(=x\left(4x^2-4x+1\right)\)

\(=x\left(2x-1\right)^2\)

\(C=x^2-6xy+9y^2-9\)

\(=\left(x-3y\right)^2-9\)

\(=\left(x-3y-3\right)\left(x-3y+3\right)\)

A=\(x^2+7x+7y-y^2=\left(x^2-y^2\right)+\left(7x+7y\right)=\left(x-y\right)\left(x+y\right)+7\left(x+y\right)=\left(x+y\right)\left(x-y+7\right)\)

B=\(4x^3-4x^2+x=x\left(4x^2-4x+1\right)=x\left(2x-1\right)^2\)

C=\(x^2+9y^2-9-6xy=\left(x^2-6xy+9y^2\right)-9=\left(x-3y\right)^2-3^2=\left(x-3y-3\right)\left(x-3y+3\right)\)

\(a,A=x^2+7x+7y-y^2\\ =x^2-y^2+7x+7y\\ =\left(x-y\right)\left(x+y\right)+7\left(x+y\right)\\ =\left(x+y\right)\left(x-y+7\right)\)

\(b,B=x^2+2xy+y^2-3x-3y\\ =\left(x+y\right)^2-3\left(x+y\right)\\ =\left(x+y\right)\left(x+y-3\right)\)

\(a,=5\left(a-4b\right)\\ b,=\left(y+1\right)^2-x^2=\left(y+1-x\right)\left(x+y+1\right)\)

a) 5a - 20b

= 5 ( a - 4b )

b) y^2 + 2y - x^2 + 1

= ( y^2 + 2y + 1 ) - x^2

= ( y + 1 )^2 - x^2

= ( y + 1 + x ) ( y + 1 - x )

a, 7x - 14

= 7(x-2)

b, 2x - 2y + \(x^2\)- xy 

= (2x-2y) + (\(x^2\)-xy)

= 2(x-y) + x(x-y)

= (x-y)(2+x)

c, 6x + 12

= 6(x+2)

\(a,=7\left(x-2\right)\\ b,=2\left(x-y\right)+x\left(x-y\right)=\left(x+2\right)\left(x-y\right)\\ c,=6\left(x+2\right)\\ d,\text{Sai đề}\)

\(a,=\left(6a^2-y\right)\left(6a^2+y\right)\\ b,=\left(x-2y\right)^2\\ c=\left(6x^2-6x\right)+\left(x-1\right)=6x\left(x-1\right)+\left(x-1\right)=\left(x-1\right)\left(6x+1\right)\)