a)2x+1/3 - 7x+5/15 = x-2/5
5(2x+1)-7x+5 = 3(x-2)
10x+5-7x+5 =3x-6
3x-3x =-6-5-5
0x =-16
=>PT vô nghiệm
b)2- 3x-7/4 + x+17/5 = 0
40 - 5(3x-7)+4(x+17)=0
40-15x+35+4x+68 =0
143-11x =0
11(13-x) =0
=>13-x=0
x =13
c)(2x+5)(x-3)/2 -x(x+3) = -1/2
(2x+5)(x-3)-2x(x+3) = -1
2x^2-6x+5x-15-2x^2-6x=-1
-7x =14
x =-2