a: =>x^2-4x+4=x^2-6x+5-4x+2
=>-4x+4=-10x+7
=>6x=3
=>x=1/2
b: =>(x+3)(5-3x)-(x+3)^2=0
=>(x+3)(5-3x-x-3)=0
=>(-4x+2)(x+3)=0
=>x=1/2 hoặc x=-3
c: =>(x-1)=3(x+3)-6+2(x-2)
=>3x+9-6+2x-4=x-1
=>5x-1=x-1
=>x=0
d: =>(x-1)(x-3)-x(x+3)=-5x+2
=>x^2-4x+3-x^2-3x=-5x+2
=>-7x+3=-5x+2
=>-2x=1
=>x=-1/2


