1. x2-x-2
=(x2-2x)+(x-2)
= x(x-2)+(x-2)
= (x+1)(x-2)
2.x2-3x+2
=x2-x-2x+2
=(x2-x)-(2x-2)
=x(x-1)-2(x-1)
=(x-2)(x-1)
3.-x2-2x+3
=3-2x-x2
=3+x-3x-x2
=(3+x)-(3x+x2)
=(3+x)-x(3+x)
=(1-x)(3+x)
4. x2-5x+4
=x2-x-4x+4
=(x2-x)-(4x-4)
=x(x-1)-4(x-1)
=(x-1)(x-4)
5. x2-5x+6
=x2-2x-3x+6
=(x2-2x)-(3x-6)
=x(x-2)-3(x-2)
=(x-2)(x-3)
6.x2-6x+5
=(x2-x)-(5x-5)
=x(x-1)-5(x-1)
=(x-1)(x-5)
7.x2-7x+12
=(x2-3x)-(4x-12)
=x(x-3)-4(x-3)
=(x-4)(x-3)
8.-x2+7x-12
=(-x2+3x)+(4x-12)
=-x(x-3)+4(x-3)
=(4-x)(x-3)
9.x2-3x-4
=(x2+x)-(4x+4)
=x(x+1)-4(x+1)
=(x-4)(x+1)
mik làm 1 nửa thôi dài quá
1) \(x^2-x-2=\left(x-2\right)\left(x+1\right)\)
2) \(x^2-3x+2=\left(x-2\right)\left(x-1\right)\)
3) \(-x^2-2x+3=-\left(x^2+2x-3\right)=-\left(x+3\right)\left(x-1\right)\)
4) \(x^2-5x+4=\left(x-1\right)\left(x-4\right)\)
5) \(x^2-5x+6=\left(x-2\right)\left(x-3\right)\)
6) \(x^2-6x+5=\left(x-1\right)\left(x-5\right)\)
7) \(x^2-7x+12=\left(x-3\right)\left(x-4\right)\)
8) \(-x^2+7x-12=-\left(x^2-7x+12\right)=-\left(x-3\right)\left(x-4\right)\)
9) \(x^2-3x-4=\left(x-4\right)\left(x+1\right)\)
10) \(x^2-4x+3=\left(x-1\right)\left(x-3\right)\)
11) \(-x^2+7x+8=-\left(x^2-7x-8\right)=-\left(x-8\right)\left(x+1\right)\)
12) \(-x^2-7x+8=-\left(x^2+7x-8\right)=-\left(x+8\right)\left(x-1\right)\)
13) \(x^2-9x+8=\left(x-1\right)\left(x-8\right)\)
14) \(-x^2-8x+9=-\left(x^2+8x-9\right)=-\left(x+9\right)\left(x-1\right)\)
15) \(x^2-10x+9=\left(x-1\right)\left(x-9\right)\)
16) \(-x^2-9x+10=-\left(x^2+9x-10\right)=-\left(x+10\right)\left(x-1\right)\)
17) \(2x^2-3x-5=\left(2x-5\right)\left(x+1\right)\)
18) \(-2x^2-3x+5=-\left(2x^2+3x-5\right)=-\left(2x+5\right)\left(x-1\right)\)
