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\(x^2+4x-y^2+4\)
\(=\left(x^2+4x+4\right)-y^2\)
\(=\left(x^2+2\right)^2-y^4\)
\(=\left(x^2+y^2+2\right)\left(x^2-y^2+2\right)\)
\(\left(x^2+4x+4\right)-y^2\)
\(=\left(x+2\right)^2-y^2\)
\(=\left(x+2+y\right)\left(x+2-y\right)\)
.
hk tôt
![](https://rs.olm.vn/images/avt/0.png?1311)
\(1)4x^2-25+\left(2x+7\right).\left(5.2x\right)\)
\(=\left(2x\right)^2-5^2-\left(2x+7\right).\left(2x-5\right)\)
\(=\left(2x.5\right)\left(2x+5\right).\left(2x+7\right)\left(2x-5\right)\)
\(=\left(2x-5\right)\left(2x+5-2x+7\right)\)
\(=\left(2x-5\right).12\)
\(2)3x+4-x^2-4x\)
\(=3(x+4)-\left(x+4\right)\)
\(=\left(3-x\right)\left(x+4\right)\)
\(3)5x^2-2y^2-10x+10y\)
\(=5\left(x^2-y^2\right)-10\left(x-4\right)\)
\(=5\left(x-y\right)\left(x+y\right)-10\left(x-y\right)\)
\(=\left(x-y\right)[5(x+y)-10]\)
Còn lại bn lm nốt nha!
![](https://rs.olm.vn/images/avt/0.png?1311)
i don't now
mong thông cảm !
...........................
![](https://rs.olm.vn/images/avt/0.png?1311)
\(2x^3y-2xy^3-4xy^2-2xy\)
\(=2xy.\left(x^2-y^2-2y-1\right)\)
\(=2xy.[x^2-\left(y^2+2y+1\right)]\)
\(=2xy.[x^2-\left(y+1\right)^2]\)
\(=2xy.\left(x+y+1\right).\left(x-y-1\right)\)
Vậy chọn đáp án A
![](https://rs.olm.vn/images/avt/0.png?1311)
\(27x^3+125y^3\)
\(=\left(3x\right)^3+\left(5y\right)^3\)
\(=\left(3x+5y\right)\left(9x^2-15xy+25y^2\right)\)
\(16x^2-24xy+9y^2\)
\(=\left(4x\right)^2-2.4x.3y+\left(3y\right)^2\)
\(=\left(4x-3y\right)^2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
(X-y-4)2-(2x+3y-1)2
=(X-Y-4-2X-3Y+1)(X-Y-4+2X+3Y-1)=(-X-4Y-3)(X+2Y-5)
(2x2+1)2+6(2x2+1)+9
=(2X2+1+3)2 (dùng hằng đẳng thức a2 +2ab+b2 =(a+b)2
=(2x2+4)2=(2(x2+2))2=4(x2+2)2
\(a,\left(x-y-4\right)^2-\left(2x+3y-1\right)^2\)
\(=\left(3x-2y-5\right)\left(-x-4y-3\right)\)
\(b,\left(2x^2+1\right)^2+6\left(2x^2+1\right)+9\)
\(=\left(2x^2+4\right)^2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)x^2-(a+b)x+ab
= x^2 - ax - bx + ab
= (x^2 - ax) - (bx - ab)
= x(x-a) - b(x-a)
= (x-b)(x-a)
b)7x^3-3xyz-21x^2+9z
=
c)4x+4y-x^2(x+y)
= 4(x + y) - x^2(x+y)
= (4-x^2) (x+y)
= (2-x)(2+x)(x+y)
d) y^2+y-x^2+x
= (y^2 - x^2) + (x+y)
= (y-x)(y+x)+ (x+y)
= (y-x+1) (x+y)
e)4x^2-2x-y^2-y
= [(2x)^2 - y^2] - (2x +y)
= (2x-y)(2x+y) - (2x+y)
= (2x -y -1)(2x+y)
f)9x^2-25y^2-6x+10y
=
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =(16x+20)^2-(10x+10)^2
=(16x+20-10x-10)(16x+20+10x+10)
=(26x+30)(6x+10)
=4(13x+15)(3x+5)
b: =(x-y+4-2x-3y+1)(x-y+4+2x+3y-1)
=(-x-4y+5)(3x+2y+3)
c: =[(x+1)^2-(x-1)^2][(x+1)^2+(x-1)^2]
=(x^2+2x+1-x^2+2x-1)(x^2+2x+1+x^2-2x+1)
=2(x^2+1)*4x
=8x(x^2+1)
Thứ nhất em làm quá tắt, thứ 2 em trình bày nó rất là khó nhìn. Em làm nhanh cho có số lượng chứ anh thấy làm thế sao mấy bạn hỏi bài hiểu được hả em? Làm bằng cái tâm nha em!
1. 2x2 - 18 = 2 • (x2 - 9) = 2 . (x-3).(x+3)
2.x2- 7xy+ 10y2=((x2) - 7xy) + (2•5y2)=(x - 2y)•(x - 5y)
3.16x3y+0.5y2 =((16 • (x3)) • y) + (— • y2) 2= y2 ((16 • (x3)) • y) +\(\dfrac{y^2}{2}\)= (24x3 • y) + \(\dfrac{y^2}{2}\)
= \(\dfrac{\text{24x3y • 2 + y2}}{2}\) =\(\dfrac{\text{32x^3y + y2}}{2}\) = 32x3y + y2 = y • (32x3 + y) = \(\dfrac{\text{y • (32x^3 + y) }}{2}\)
4.x4-4x3+4x2 = ((x4) - (4 • (x3))) + 22x2 =((x4) - 22x3) + 22x2 = x4 - 4x3 + 4x2
= x2 • (x2 - 4x + 4) = x2 • (x - 2)2
5.2ab2-a2b-b3 = (2ab2 - a2b) - b3
= -a2b + 2ab2 - b3 = -b • (a2 - 2ab + b2)
= -b • (a - b)2
Nhớ cho đúng nha