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19 tháng 10 2017

\(\text{a) }ax-bx+ab-x^2\\ \\=\left(ax+ab\right)-\left(x^2+bx\right)\\ \\=a\left(x+b\right)-x\left(x+b\right)\\ \\=\left(a-x\right)\left(x+b\right)\\ \)

\(\text{b) }x^2-y^2+4x+4\\ \\ =\left(x^2+4x+4\right)-y^2\\ \\ =\left(x+2\right)^2-y^2\\ \\ =\left(x+2+y\right)\left(x+2-y\right)\\ \)

\(\text{c) }ax+ay-3x-3y\\ \\=\left(ax+ay\right)-\left(3x+3y\right)\\ \\ =a\left(x+y\right)-3\left(x+y\right)\\ \\=\left(a-3\right)\left(x+y\right)\\ \)

\(\text{d) }x^3+x^2+x+1\\ \\=\left(x^3+x^2\right)+\left(x+1\right)\\ \\=x^2\left(x+1\right)+\left(x+1\right)\\ \\=\left(x^2+1\right)\left(x+1\right)\\ \)

\(\text{e) }x^3-3x^2+3x-9\\ \\=\left(x^3-3x^2\right)+\left(3x-9\right)\\ \\ =x^2\left(x-3\right)+3\left(x-3\right)\\ \\=\left(x^2+3\right)\left(x-3\right)\\ \)

\(\text{f) }x^2+ab+ax+bx\\ \\=\left(x^2+ax\right)+\left(bx+ab\right)\\ \\ =x\left(x+a\right)+b\left(x+a\right)\\ \\=\left(x+b\right)\left(x+a\right)\\ \)

\(\text{g) }xy+1+x+y\\ \\=\left(xy+x\right)+\left(y+1\right)\\ \\=x\left(y+1\right)+\left(y+1\right)\\ \\=\left(x+1\right)\left(y+1\right)\)

\(\text{h) }9-x^2-2xy-y^2\\ \\=9-\left(x^2+2xy+y^2\right)\\ \\=3^2-\left(x+y\right)^2\\ \\=\left(3-x-y\right)\left(3+x+y\right)\\ \)

\(\text{i) }x^2-2xy+y^2-1\\ \\=\left(x^2-2xy+y^2\right)-1\\ \\=\left(x-y\right)^2-1^2\\ \\=\left(x-y-1\right)\left(x-y+1\right)\\ \)

19 tháng 10 2017

d) x3 + x2 + x + 1

= x2(x + 1) + (x + 1)

= (x + 1)(x2 + 1)

e) x3 - 3x2 + 3x - 9

= x2(x - 3) + 3(x - 3)

= (x - 3)(x2 + 3)

f) x2 + ab + ax + bx

= x2 + bx + ab + ax

= x(x + b) + a(b + x)

= (b + x)(x + a)

g) xy + 1 + x + y

= xy + x + y + 1

= x(y + 1) + (y + 1)

= (y + 1)(x + 1)

h) 9 - x2 - 2xy - y2

= 9 - (x2 + 2xy + y2)

= 32 - (x + y)2

= (3 - x - y)(3 + x + y)

i) x2 - 2xy + y2 - 1

= (x - y)2 - 1

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

17 tháng 7 2019

\(a,xy+1-x-y\)

\(=\left(xy-y\right)+\left(1-x\right)\)

\(=y\left(x-1\right)- \left(x-1\right)\)

\(=\left(x-1\right)\left(y-1\right)\)

\(b,ax+ay-3x-3y\)

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

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

\(c,x^3-2x^2+2x-4\)

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

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

\(d,x^2+ab+ax+bx\)

\(=\left(x^2+ax\right)+\left(ab+bx\right)\)

\(=x\left(a+x\right)+b\left(a+x\right)\)

\(=\left(a+x\right)\left(b+x\right)\)

\(e,16-x^2+2xy-y^2\)

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

\(=4^2-\left(x-y\right)^2\)

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

17 tháng 7 2019

\(f,ax^2+ax-bx^2-bx-a+b\)

\(=\left(ax^2-bx^2\right)+\left(ax-bx\right)-\left(a-b\right)\)

\(=x^2\left(a-b\right)+x\left(a-b\right)-\left(a-b\right)\)

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

8 tháng 9 2020

A = xy + y - 2x - 2

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

= ( x + 1 )( y - 2 )

B = x2 - 3x + xy - 3y

= x( x - 3 ) + y( x - 3 )

= ( x - 3 )( x + y )

C = 3x2 - 3xy - 5x + 5y

= 3x( x - y ) - 5( x - y )

= ( x - y )( 3x - 5 )

D = xy + 1 + x + y

= y( x + 1 ) + ( x + 1 )

= ( x + 1 )( y + 1 )

E = ax - bx + ab - x2

= ( ax - x2 ) + ( ab - bx )

= x( a - x ) + b( a - x )

= ( a - x )( x + b )

F = x2 + ab + ax + bx

= ( ax + x2 ) + ( ab + bx )

= x( a + x ) + b( a + x )

= ( a + x )( x + b )

G = a3 - a2x - ay + xy

= a2( a - x ) - y( a - x )

= ( a - x )( a2 - y )

Bonus : = ( a - x )[ a2 - ( √y )2 ]

             = ( a - x )( a - √y )( a + √y )

H = 2xy + 3z + 6y + xz

= ( 6y + 2xy ) + ( 3z + xz )

= 2y( 3 + x ) + z( 3 + x )

= ( 3 + x )( 2y + z )

8 tháng 9 2020

A = xy + y - 2x - 2 = y(x + 1) - 2(x + 1) = (y - 2)(x + !1

B = x2 - 3x + xy - 3y = x(x - 3) + y(x - 3) = (x + y)(x - 3)

C = 3x2 - 3xy - 5x + 5y = 3x(x - y) - 5(x - y) = (3x - 5)(x - y)

D = xy + 1 + x + y = xy + x + y + 1 = x(y + 1) + (y + 1) = (x + 1)(y + 1)

E = ax - bx + ab - x2 = ax - x2 + ab - bx = a(a - x) - b(a - x) = (a - b)(a - x)

F = x2 + ab + ax + bx = ab + ax + bx + x2 = a(b + x) + x(b + x) = (a + x)(b + x)

G = a3 - a2x - ay + xy = a2(a - x) - y(a - x) = (a2 - y)(a - x)

H = 2xy + 3z + 6y + xz = 2xy + 6y + 3z + xz = 2y(x + 3) + z(x + 3) = (2y + z)(x + 3)

17 tháng 7 2019

Hỏi đáp Toán

17 tháng 7 2019

a) \(xy+1-x-y\)

\(=x\left(y-1\right)-\left(y-1\right)\)

\(=\left(y-1\right)\left(x-1\right)\)

b) \(ax+ay-3x-3y\)

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

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

c) \(x^3-2x^2+2x-4\)

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

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

d) \(x^2+ab+ax+bx\)

\(=x\left(b+x\right)+a\left(b+x\right)\)

\(=\left(b+x\right)\left(a+x\right)\)

e) \(16-x^2+2xy-y^2\)

\(=16-\left(x^2-2xy+y^2\right)\)

\(=4^2-\left(x-y\right)^2\)

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

f) \(ax^2+ax-bx^2-bx-a+b\)

\(=\left(ax^2+ax-a\right)-\left(bx^2+bx-b\right)\)

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

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

1 tháng 8 2019

a) \(x^2-6x-y^2+9\)

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

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

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

1 tháng 8 2019

b) \(9-x^2+2xy-y^2\)

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

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

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

1: \(=a\left(x+y\right)-4\left(x+y\right)=\left(x+y\right)\left(a-4\right)\)

2: \(=x\left(x+b\right)+a\left(x+b\right)=\left(x+b\right)\left(x+q\right)\)

3: \(=a\left(x+1\right)-b\left(x+1\right)+c\left(x+1\right)\)

\(=\left(x+1\right)\left(a-b+c\right)\)

6: \(=\left(x-y\right)^2-4=\left(x-y-2\right)\left(x-y+2\right)\)

a) Ta có: \(\left(3x-1\right)^2-16\)

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

\(=\left(3x-5\right)\left(3x+3\right)\)

\(=3\left(x+1\right)\left(3x-5\right)\)

b) Ta có: \(\left(5x-4\right)^2-49x^2\)

\(=\left(5x-4-7x\right)\left(5x-4+7x\right)\)

\(=\left(-2x-4\right)\left(12x-4\right)\)

\(=-2\left(x+2\right)\cdot4\cdot\left(3x-1\right)\)

\(=-8\left(x+2\right)\left(3x-1\right)\)

c) Ta có: \(\left(2x+5\right)^2-\left(x-9\right)^2\)

\(=\left(2x+5-x+9\right)\left(2x+5+x-9\right)\)

\(=\left(x+14\right)\left(3x-4\right)\)

d) Ta có: \(\left(3x+1\right)^2-4\left(x-2\right)^2\)

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

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

\(=\left(x+5\right)\left(5x-3\right)\)

e) Ta có: \(9\left(2x+3\right)^2-4\left(x+1\right)^2\)

\(=\left(6x+9\right)^2-\left(2x+2\right)^2\)

\(=\left(6x+9-2x-2\right)\left(6x+9+2x+2\right)\)

\(=\left(4x+7\right)\left(8x+11\right)\)

f) Ta có: \(4b^2c^2-\left(b^2+c^2-a^2\right)^2\)

\(=\left(2bc-b^2-c^2+a^2\right)\left(2bc+b^2+c^2-a^2\right)\)

\(=-\left(b^2-2bc+c^2-a^2\right)\left[\left(b^2+2bc+c^2\right)-a^2\right]\)

\(=-\left[\left(b-c\right)^2-a^2\right]\cdot\left[\left(b+c\right)^2-a^2\right]\)

\(=-\left(b-c-a\right)\left(b-c+a\right)\left(b+c-a\right)\left(b+c+a\right)\)

g) Ta có: \(\left(ax+by\right)^2-\left(ay+bx\right)^2\)

\(=\left(ax+by-ay-bx\right)\left(ax+by+ay+bx\right)\)

\(=\left[a\left(x-y\right)+b\left(y-x\right)\right]\left[a\left(x+y\right)+b\left(x+y\right)\right]\)

\(=\left[a\left(x-y\right)-b\left(x-y\right)\right]\left(x+y\right)\left(a+b\right)\)

\(=\left(x-y\right)\left(a-b\right)\left(x+y\right)\left(a+b\right)\)

h) Ta có: \(\left(a^2+b^2-5\right)^2-4\left(ab+2\right)^2\)

\(=\left(a^2+b^2-5\right)^2-\left(2ab+4\right)^2\)

\(=\left(a^2+b^2-5+2ab+4\right)\left(a^2+b^2-5-2ab-4\right)\)

\(=\left[\left(a^2+2ab+b^2\right)-1\right]\left[\left(a^2-2ab+b^2\right)-9\right]\)

\(=\left(a+b-1\right)\left(a+b+1\right)\left(a-b-3\right)\left(a-b+3\right)\)

i) Ta có: \(\left(4x^2-3x-18\right)^2-\left(4x^2+3x\right)^2\)

\(=\left(4x^2-3x-18-4x^2-3x\right)\left(4x^2-3x-18+4x^2+3x\right)\)

\(=\left(-6x-18\right)\left(8x^2-18\right)\)

\(=-6\left(x+3\right)\cdot2\left(x^2-9\right)\)

\(=-12\left(x+3\right)^2\cdot\left(x-3\right)\)

k) Ta có: \(9\left(x+y-1\right)^2-4\left(2x+3y+1\right)^2\)

\(=\left(3x+3y-3\right)^2-\left(4x+6y+2\right)^2\)

\(=\left(3x+3y-3-4x-6y-2\right)\left(3x+3y-3+4x+6y+2\right)\)

\(=\left(-x-3y-5\right)\left(7x+9y-1\right)\)

l) Ta có: \(-4x^2+12xy-9y^2+25\)

\(=-\left(4x^2-12xy+9y^2-25\right)\)

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

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

m) Ta có: \(x^2-2xy+y^2-4m^2+4mn-n^2\)

\(=\left(x-y\right)^2-\left(4m^2-4mn+n^2\right)\)

\(=\left(x-y\right)^2-\left(2m-n\right)^2\)

\(=\left(x-y-2m+n\right)\left(x-y+2m-n\right)\)

21 tháng 8 2017

a)\(\left(3x-1\right)^2-16=\left(3x-1-16\right)\left(3x-1+16\right)\)

                                     \(=\left(3x-17\right)\left(3x+15\right)\)

c)\(\left(2x+5\right)^2-\left(x-9\right)^2=\left(2x+5+x-9\right)\left(2x+5-x+9\right)\)

                                                 \(=\left(x-4\right)\left(x+14\right)\)

      Aps dungj t/c a2 - b2 = ( a-b)(a+b)

10 tháng 10 2016

a) \(ax+ay-3x-3y=a\left(x+y\right)-3\left(x+y\right)=\left(a-3\right)\left(x+y\right)\)

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

c) xem lại đề

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