a) (x-3)(x-5)-(2x+1)(x-3) = 0
<=>(x-3)(x-5-2x+1)=0
<=>-(x-3)(x-4)=0
<=>x-3=0 <=>x=3
x-4=0 x=4
Vậy x=3;x=4
b)Nó kiểu j ý bạn
c) (x+2)(2x-1)+1= 4x^2
<=>(x+2)(2x-1)+1-4x^2=0
<=>(x+2)(2x-1)-(4x^2-1)=0
<=>(x+2)(2x-1)-(2x+1)(2x-1)=0
<=>(2x-1)(x+2-2x-1)=0
<=>(2x-1)(1-x)=0
<=>2x-1=0 <=>x=1/2
1-x=0 x=1
Vậy x=1/2; x=1