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1) Phân tích đa thức thành nhân tử
a) \(x^2+2x+1-y^2\)
b) \(x^2+4x+3\)
c) \(4x^2-9y^2\)
d) \(x^3-27y^3\)
a) \(x^2+2x+1-y^2=\left(x+1\right)^2-y^2=\left(x+1-y\right)\left(x+1+y\right)\)
b) \(x^2+4x+3=x^2+4x+4-1=\left(x+2\right)^2-1=\left(x+1\right)\left(x+3\right)\)
c) \(4x^2-9y^2=\left(4x-9y\right)\left(4x+9y\right)\)
d) \(x^3-27y^3=\left(x-3y\right)\left(x^2+3xy+9y^2\right)\)
a)\(x^2+2x+1-y^2=\left(x+1\right)^2-y^2=\left(x+y-1\right)\left(x-y+1\right)\)
b)\(x^2+4x+3=\left(x+1\right)\left(x+3\right)\)
c)\(4x^2-9y^2=\left(2x-3y\right)\left(2x+3y\right)\)
d)\(x^3-27y^3=\left(x-3y\right)\left(x^2+3xy+9y^2\right)\)
\(x^2-y^2+4-4x\)
\(=\left(x^2-4x+4\right)-y^2\)
\(=\left(x-2\right)^2-y^2\)
\(=\left(x-2+y\right)\left(x-2-y\right)\)
1)=x(x-1)-y(y-1)
2)=(x-2)2 -y2
3)=(2x+1)2 -9y2+1
#Mình k biết viết bình phương, thông cảm bạn nhé!
\(e,-5x+x^2-14\)
\(=x^2+2x-7x-14\)
\(=x\left(x+2\right)-7\left(x+2\right)\)
\(=\left(x+2\right)\left(x-7\right)\)
\(f,x^3+8+6x\left(x+2\right)\)
\(=\left(x+2\right)\left(x^2+2x+4\right)+6x\left(x+2\right)\)
\(=\left(x+2\right)\left(x^2+8x+4\right)\)
\(g,15x^2-7xy-2y^2\)
\(=15x^2+3xy-10xy-2y^2\)
\(=3\left(5x+y\right)-2y\left(5x+y\right)\)
\(=\left(5x+y\right)\left(3-2y\right)\)
\(h,3x^2-16x+5\)
\(=3x^2-x-15x+5\)
\(=x\left(3x-1\right)+5\left(3x-1\right)\)
\(=\left(3x-1\right)\left(x+5\right)\)
\(a,x^3+2x^2y+xy^2=x\left(x^2+2xy+y^2\right)\)
\(=x\left(x+y\right)^2\)
\(b,4x^2-9y^2+4x-6y\)
\(=4x^2+4x+1-\left(9y^2+6y+1\right)\)
\(=\left(2x+1\right)^2-\left(3y+1\right)^2\)
\(=\left(2x-3y\right)\left(2x+3y+2\right)\)
\(c,-x^2+5x+2xy-5y-y^2\)
\(=-\left(x^2-2xy+y^2\right)+5\left(x-y\right)\)
\(=-\left(x-y\right)^2+5\left(x-y\right)\)
\(=\left(x-y\right)\left(y-x+5\right)\)
\(d,x^2+4x-12\)
\(=x^2-2x+6x-12\)
\(=x\left(x-2\right)+6\left(x-2\right)\)
\(=\left(x-2\right)\left(x+6\right)\)
Ta có: \(4x^2-9y^2\\ =\left(2x\right)^2-\left(3y\right)^2\\ =\left(2x-3y\right)\left(2x+3y\right)\)
Vậy: Chọn D
a,x2-4xy+4y2
=(x-2y2
b,4x4+9y2-12x2y
=(2x2)2+(3y)2-12x2y
(2x2-3y)
a) 3x2 - 15x3 = 3x2.( 1 - 5x )
b) x.( 2x - 3 ) + y.( 3 - 2x ) = x.( 2x - 3 ) - y.( 2x - 3 ) = ( 2x - 3 ).( x - y )
c) ( 5x - y )2 - 4x2 = ( 5x - y )2 - ( 2x )2 = ( 5x - y - 2x ).( 5x - y + 2x ) = ( 3x - y ).( 7x - y )
d) x2 - 9y2 + 4 - 4x = ( x2 - 4x + 4 ) - 9y2 = ( x - 2 )2 - ( 3y )2 = ( x - 2 - 3y ).( x - 2 + 3y )
a) = (4x2 +4x + 1) - (9y2 + 6y + 1) = (2x+ 1)2 - (3y + 1)2 = (2x+ 1+ 3y + 1).(2x + 1 - 3y - 1) = (2x+ 3y+ 2).(2x-3y)
b) = x2 - 2015x + 2014x - 2014.2015 = x.(x - 2015) + 2014. (x - 2015) = (x + 2014).(x - 2015)
\(b,x^2-4x-9y^2+4=\left(x-2\right)^2-\left(3y\right)^2=\left(x-2-3y\right)\left(x-2+3y\right)\)
\(c,x^2-2x-4x^2+1=\left(x-1\right)^2-\left(2x\right)^2=\left(x-1+2x\right)\left(x-2x-1\right)=\left(3x-1\right)\left(-x-1\right)\)
\(d,4x^2-6x-9y^2+9y=\left(4x^2-9y^2\right)-\left(6x-9y\right)=\left(2x-3y\right)\left(2x+3y\right)-3\left(2x-3y\right)=\left(2x+3y-3\right)\left(2x-3y\right)\)