Đáp án:
1/x^2+2x-4=-12+3x+x^2
⇔x^2+2x-4+12-3x-x^2=0
⇔-x+8=0⇔x=8
2/x(x-1)-x(x+3)=15
⇔x(x-1-x-3)=15
⇔-4x=15⇔x=15/-4
3/x(x-1)=x(x+3)
⇔x(x-1)-x(x+3)=0
⇔x(x-1-x-3)=0
⇔-4x=0⇔x=0
4/x(2x-3)-x^2+2=x(x-5)-1
⇔2x^2-3x-x^2+2-x^2+5x+1=0
⇔2x+3=0⇔x=-3/2
5/(x-1)(x+3)=x^2-4
⇔x^2+2x-3-x^2+4=0
⇔2x+1=0⇔x=-1/2
6/(x-2)(x-5)=(x-3)(x-4)
⇔x^2-7x+10-x^2+7x-12=0
⇔-2=0⇒PT vô nghiệm
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