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SG
2
GD
19 tháng 7 2017
a) \(x^2+5x-6\)
\(=x^2-2x+3x-6\\ =\left(x^2-2x\right)+\left(3x-6\right)\\ =x\left(x-2\right)+3\left(x-2\right)\\ =\left(x-2\right)\left(x+3\right)\)
b) \(5x^2+5xy-x-y\)
\(=\left(5x^2+5xy\right)-\left(x+y\right)\\ =5x\left(x+y\right)-\left(x+y\right)\\ =\left(x+y\right)\left(5x+1\right)\)
c)\(7x-6x^2-2\)
\(=3x+4x-6x^2-2\\ =\left(3x-6x^2\right)+\left(4x-2\right)\\ =3x\left(1-2x\right)+2\left(2x-1\right)\\ =3x\left(1-2x\right)-2\left(1-2x\right)\\ =\left(1-2x\right)\left(3x-2\right)\)
PT
3
NN
0
HK
1
18 tháng 8 2017
x3 + 7x - 6=x2 . x + 7x - 22 + 2 = (x2 - 22) + (x+7x)+2=(x-2) . (x+2) + 8x + 2
x3 - 5x + 8x - 4=x2 . x -5x + 8x -22 = (x2 - 22) . (x -5x + 8x )=(x-2) . (x+2) . 4x
x3 - 9x2 + 6x + 16=x2 . x - 9x2 + 6x + 16 = (x2 - 9x2) . (x+6x) + 16=(x-9x) . (x+9x) . 7x + 16
k mk nha
W
5
20 tháng 7 2019
\(x^2+5x-6=x^2-x+6x-6=x\left(x-1\right)+6\left(x-1\right)=\left(x+6\right)\left(x-1\right)\)
\(5x^2+5xy-x-y=5x\left(x+y\right)-\left(x+y\right)=\left(5x-1\right)\left(x+y\right)\)
\(7x-6x^2-2=3x-6x^2+4x-2=3x\left(1-2x\right)-2\left(1-2x\right)=\left(3x-2\right)\left(1-2x\right)\)
20 tháng 7 2019
\(a,x^2+5x-6=x^2-x+6x-6\)
\(=x\left(x-1\right)+6\left(x-1\right)=\left(x-1\right)\left(x+6\right)\)
\(b,5x^2+5xy-x-y=5x\left(x+y\right)-\left(x+y\right)\)
\(=\left(x+y\right)\left(5x-1\right)\)
\(c,7x-6x^2-2=-6x^2+3x+4x-2\)
\(=-3x\left(2x-1\right)+2\left(2x-1\right)=\left(2x-1\right)\left(2-3x\right)\)
YN
26 tháng 11 2021
Answer:
Câu đầu bạn xem lại.
\(\left(3x+4\right)^2+\left(4x-3\right)^2+\left(2+5x\right).\left(2-5x\right)\)
\(=\left(3x\right)^2+2.2x.4+4^2+\left(4x\right)^2-2.4x.3+3^2+2^2-\left(5x\right)^2\)
\(=9x^2+24x+16+16x^2-24x+9+4-25x^2\)
\(=\left(9x^2+16x^2-25x^2\right)+\left(24x-24x\right)+\left(16+9+4\right)\)
\(=29\)
\(\left(5x+y\right).\left(25x^2-5xy+y^2\right)-\left(5x-y\right).\left(25x^2+5xy+y^2\right)\)
\(=\left(5x+y\right).[\left(5x\right)^2-5x.y+y^2]-\left(5x-y\right).[\left(5x\right)^2+5x.y+y^2]\)
\(=\left(5x\right)^3+y^3-[\left(5x\right)^3-y^3]\)
\(=\left(5x\right)^3+y^3-\left(5x\right)^3+y^3\)
\(=2y^3\)
5 tháng 10 2020
a) 5x2 - 5xy + 7y - 7x = ( 5x2 - 5xy ) - ( 7x - 7y ) = 5x( x - y ) - 7( x - y ) = ( x - y )( 5x - 7 )
b) x2 - y2 + 2x + 1 = ( x2 + 2x + 1 ) - y2 = ( x + 1 )2 - y2 = ( x - y + 1 )( x + y + 1 )
c) 3x2 + 6xy + 3y2 - 3z2 = 3( x2 + 2xy + y2 - z2 ) = 3[ ( x2 + 2xy + y2 ) - z2 ] = 3[ ( x + y )2 - z2 ] = 3( x + y - z )( x + y + z )
d) ab( x2 + y2 ) + xy( a2 + b2 ) = abx2 + aby2 + a2xy + b2xy
= ( a2xy + abx2 ) + ( aby2 + b2xy )
= ax( ay + bx ) + by( ay + bx )
= ( ay + bx )( ax + by )
DD
Đoàn Đức Hà
Giáo viên
8 tháng 10 2021
a) \(x^2+8x+15=x^2+3x+5x+15=\left(x+3\right)\left(x+5\right)\)
b) \(x^2+3x+2=x^2+2x+x+2=\left(x+1\right)\left(x+2\right)\)
c) \(-x^2+7x-6=-x^2+x+6x-6=\left(-x+6\right)\left(x-1\right)\)
d) \(5x^3y-10x^2y^2+5xy^3=5xy\left(x^2-2xy+y^2\right)=5xy\left(x-y\right)^2\)
e) \(2x^2+7x-15=2x^2-3x+10x-15=\left(2x-3\right)\left(x+5\right)\)
3 tháng 7 2018
1) \(x^2+6x+8\)
\(=x^2+2x+4x+8\)
\(=x\left(x+2\right)+4\left(x+2\right)\)
\(=\left(x+4\right)\left(x+2\right)\)
2) \(x^2-5x-14\)
\(=x^2-7x+2x-14\)
\(=x\left(x-7\right)+2\left(x-7\right)\)
\(=\left(x-7\right)\left(x+2\right)\)
3 tháng 7 2018
3) \(2x^2+5x+3\)
\(=2x^2+2x+3x+3\)
\(=2x\left(x+1\right)+3\left(x+1\right)\)
\(=\left(x+1\right)\left(2x+3\right)\)
4) \(x^2-x-12\)
\(=x^2-4x+3x-12\)
\(=x\left(x-4\right)+3\left(x-4\right)\)
\(=\left(x-4\right)\left(x+3\right)\)
\(x^2+5x-6=x^2-6x+x-6=x\left(x-6\right)+\left(x-6\right)=\left(x+1\right)\left(x-6\right)\)
\(5x^2+5xy-x-y=5x\left(x+y\right)-\left(x+y\right)=\left(5x-1\right)\left(x+y\right)\)
\(7x-6x^2-2=-6x^2+7x-2=-6\left(x^2-\frac{7}{6}x+\frac{1}{3}\right)=-6\left(x^2-\frac{7}{6}x+\frac{49}{144}-\frac{1}{144}\right)=-6\left[\left(x-\frac{7}{12}\right)^2-\frac{1}{144}\right]\)
1) x2-x+6x-6 = x(x-1)+6(x-1)=(x+6)(x-1)
2) 5x(x+y)-(x+y) =(5x-1)(x+y)
3) -6x2+7x-2 = -6x2+3x+4x-2= -6x(x-\(\frac{1}{2}\)) +4(x-\(\frac{1}{2}\)) =(-3x+2)(2x-1)