1/ \(\left(x+3\right)^2-\left(2x-5\right)\left(x+3\right).\)
\(=x^2+6x+9-\left(2x^2+6x-5x-15\right)\)
\(=x^2+6x+9-2x^2-6x+5x+15\)
\(=-x^2+5x+24\)
\(=-\left(x^2-5x-24\right)\)
\(=-\left(x^2-8x+3x-24\right)\)
\(=-\left[x\left(x-8\right)+3\left(x-8\right)\right]\)
\(=-\left(x-8\right)\left(x+3\right)\)
2/ \(x^2-xy+x-y\)
\(=\left(x^2+x\right)-\left(xy+y\right)\)
\(=x\left(x+1\right)-y\left(x+1\right)\)
\(=\left(x-y\right)\left(x+1\right)\)
3/ \(x^3+6x^2+9x\)
\(=x\left(x^2+6x+9\right)\)
\(=x\left(x+3\right)^2\)
1,Bạn tự lm
\(2,x^2-xy+x-y=x\left(x-y\right)+\left(x-y\right)=\left(x-1\right)\left(x+1\right)\)
\(3,x^3+6x^2+9x=x\left(x^2+6x+9\right)=x\left(x+3\right)^2\)
\(4,x^2y+xy+x+1=xy\left(x+1\right)+\left(x+1\right)=\left(x+1\right)\left(xy+1\right)\)
\(5,ax+by+ay+bx=\left(ax+ay\right)+\left(by+bx\right)=a\left(x+y\right)+b\left(y+x\right)=\left(x+y\right)\left(a+b\right)\)
\(6,x^2-\left(a+b\right)x+ab=x^2-ax-bx+ab=\left(x^2-bx\right)-\left(ax-ab\right)=x\left(x-b\right)-a\left(x-b\right)=\left(x-b\right)\left(x-a\right)\)
1, (x+3)2-(2x-5)(x+3)
<=>(x+3)(x+3-2x+5)
<=>(x+3)(-x+8)
2, x2-xy+x-y
<=>x(x-y)+(x-y)
<=>(x-y)(x+1)
3, x3+6x2+9x
<=>x(x2+6x+9)
<=>x(x+3)2
4/ \(x^2y+xy+x+1\)
\(=\left(x^2y+xy\right)+\left(x+1\right)\)
\(=xy\left(x+1\right)+\left(x+1\right)\)
\(=\left(x+1\right)\left(xy+1\right)\)
5/\(ax+by+ay+bx\)
\(=\left(ax+ay\right)+\left(bx+by\right)\)
\(=a\left(x+y\right)+b\left(x+y\right)\)
\(=\left(a+b\right)\left(x+y\right)\)
6/ \(x^2-\left(a+b\right)x+ab\)
\(=x^2-ax-bx+ab\)
\(=\left(x^2-ax\right)-\left(bx-ab\right)\)
\(=x\left(x-a\right)-b\left(x-a\right)\)
\(=\left(x-b\right)\left(x-a\right)\)
