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![](https://rs.olm.vn/images/avt/0.png?1311)
bài 2 :
0,25x3+x2+x=0
<=>0,25x3+0,5x2+0,5x2+x=0
<=>0,25x2(x+2)+0,5x(x+2)=0
<=>(x+2)(0,25x2+0,5x)=0
<=>(x+2)x(0,25x+0,5)=0
<=>x+2=0 hoặc x=0 hoặc 0,25x+0,5=0
=>x=-2 hoặc x=0 hoặc x=-2
vậy x=0 hoặc x=-2
![](https://rs.olm.vn/images/avt/0.png?1311)
\(=\left[\left(x+y\right)^3-1\right]-3xy\left(x+y-1\right)\)
\(=\left(x+y-1\right)\left[\left(x+y\right)^2+1+2\left(x+y\right)\right]-3xy\left(x+y-1\right)\)
\(=\left(x+y-1\right)\left(x^2+y^2+2xy+1+2x+2y-3xy\right)\)
\(=\left(x+y+1\right)\left(x^2+y^2-xy+1+2x+2y\right)\)
\(=\left(x+y-1\right)\left[\left(x^2+1+2x\right)\left(y^2-xy+2y\right)\right]\)
\(=\left(x+y-1\right)\left(x+1\right)^2\left(y-x+2\right)y\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(xy+y^2-x-y=y\left(x+y\right)-\left(x+y\right)=\left(x+y\right)\left(y-1\right)\)
b) \(25-x^2+4xy-4y^2=25-\left(x-2y\right)^2=\left(5-x+2y\right)\left(5+x-2y\right)\)
c) \(x^2-4x+3=x^2-x-3x+3=x\left(x-1\right)-3\left(x-1\right)=\left(x-1\right)\left(x-3\right)\)
d) \(y^2\left(x-1\right)-7y^3+7xy^3\)
\(=y^2\left(x-1-7y+7xy\right)\)
\(=y^2\left[\left(x-1\right)-7y\left(1-x\right)\right]=y^2\left(x-1\right)\left(1+7y\right)\)
a)
\(xy+y^2-x-y\\ =\left(xy-x\right)+\left(y^2-y\right)\\ =x\left(y-1\right)+y\left(y-1\right)\\ =\left(y-1\right)\left(x+y\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
h) \(y\left(y-x\right)^3-x\left(x-y\right)^2+xy\left(x-y\right)=y\left(y-x\right)^3-x\left(y-x\right)^2-xy\left(y-x\right)=\left(y-x\right)\left[y\left(y-x\right)^2-x-xy\right]=\left(y-x\right)\left[y\left(y^2-2xy+x^2\right)-x-xy\right]=\left(y-x\right)\left(y^3-2xy^2+x^2y-x-xy\right)\)
i) \(10x^2\left(a-2b\right)^2-\left(x^2+2\right)\left(2b-a\right)^2=10x^2\left(a-2b\right)^2-\left(x^2+2\right)\left(a-2b\right)^2=\left(a-2b\right)^2\left(10x^2-x^2-2\right)=\left(a-2b\right)^2\left(9x^2-2\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\left(2x+5\right)^2\)\(-\left(x-9\right)^2\)
=\(\left(2x+5+x-9\right).\left(2x+5-x+9\right)\)
=\(\left(3x-4\right).\left(x+14\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
đề sai rùi phải là : \(36\left(x-y\right)^2-25\left(2x-1\right)^2\)
\(=>\left[6\left(x-y\right)\right]^2-\left[5\left(2x-1\right)\right]^2=\left[6\left(x-y\right)-5\left(2x-1\right)\right]\left[6\left(x-y\right)+5\left(2x-1\right)\right]\)
\(=>\left(6x-6y-10x+5\right)\left(6x-6y+10x-5\right)=\left(5-4x-6y\right)\left(16x-6y-5\right)\)
Áp dụng HDT : x^2 -y^2 =(x-y) (x+y)
Ủng hộ = 1 cái t i c k nha cảm ơn
Ta có : x3 - 0,25x = 0
=> x(x2 - 0,25) = 0
=> x(x - 0,5)(x + 0,5) = 0
<=> x = 0
x - 0,5 = 0
x + 0,5 = 0
<=> x = 0
x = 0,5
x = -0,5
Bạn làm tiếp hộ mình với =(( mình chưa hiểu lắm câu 28b