3x/2x^2 + 1 + 2x^2+1/4 = 4( đề bài )
3x/2x^2 +1+ 2x^2+1/4 = 4 ; x khác 0
3/2x+1+2x^2+1/4 = 4
3/2x+1+2x^2+1/4-4 = 0
3/2x-3+2x^2+1/4 = 0
6-12x+x.(2x^2+1)/4x = 0
6-12x+2x^3+x/4x = 0
6-11x+2x^3/4x = 0
6-11x+2x^3 = 0
2x^3-11x+6 = 0
2x^3-4x^2+4x^2-8x-3x+6 = 0
2x^2.( x-2)+4x.(x-2)-3(x-2) = 0
(x-2) . ( 2x^2+4x-3) = 0
<=> x-2 = 0 hay 2x^2=4x-3 = 0
<=> x=2 hay x= (-2+căn10)/2 hay x= (-2-căn10)/2