a) 2x+4(x-2)=5
<=>2x+4(x-2)=5
<=>2x+4x-8=5
<=>6x-13=0
<=>x=13/6
Vậy S={13/6}
b)(x+2)^2-2(x-3)=(x+1)^2
<=>x^2+4x+2^2-4x^2-6x=x^2+2x+1
<=>x^2+4x+2^2-4x^2-6x-x^2-2x-1=0
<=>4x^2+4x-3=0
<=4x^2-2x+6x-3=0
<=>2x(2x-1)+3(2x-1)=0
<=>(2x-1)(2x+3)=0
<=>[2x-1=0<=>[2x=1<=>[x=1/2
[2x+3=0 [2x=-3 [x=-3/2
Vậy S={1/2;-3/2}
c)x+2/x-2 -1/x=2/x (x-2)
<=>x(x+2)/x(x-2)-x-2/x(x-2)=2/x(x-2)
<=>x^2+2x-x+2-2=0
<=>x^2+x=0
<=>x(x+1)=0
<=>x=-1
x=0
Vậy S={-1;0}
d)3x^2-2x-1=0 ko bt lm (o_o)!
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