a) (4x-3)(2x-1) = (x-3)(4x-3)
<=> (4x-3)(2x-1) - (x-3)(4x-3) = 0
<=> (4x-3)(2x-1-x+3) = 0
<=> 4x-3 = 0 => x = 3/4
2x-1-x+3 = 0 <=> x + 2 = 0 => x = -2
Vậy S = {3/4;-2}
b) 25x^2 - 9 = (5x+3)(2x+1)
<=> (5x-3)(5x+3) = (5x-3)(2x+1)
<=> (5x-3)(5x+3) - (5x-3)(2x+1)=0
<=> (5x-3)(5x+3-2x-1) = 0
<=> 5x-3=0 => x = 3/5
5x+3-2x-1=0 => 3x+2=0
=> x = -2/3
Vậy S = {3/5;-2/3}
c) (3x-4)^2 - 4(x+1)^2 = 0
<=> 9x^2-24x+16-[4(x^2+2x+1)]=0
<=> 9x^2-24x+16-4x^2-8x-4=0
<=> 5x^2-32x+12=0
<=> (x-6)(5x-2) = 0
<=> x-6=0 => x = 6
5x-2=0 => x = 2/5
Vậy S = {6;2/5}
d) x^4+2x^3-x-2=0
<=> x^3(x+2)-(x+2)=0
<=> (x+2)(x^3-1)=0
<=> x+2=0 => x = -2
x^3-1=0 => x=1
Vậy S = {-2;1}
