a (1-x )/(x+1)+3 = (2x+3)/(x+1) b (x+1)/(x-2)= 1/(x^2-4)
(=) (1-x)/x+1+3(x+1)/x+1= 2x+3/x+1 (=)(x+1)(x+2)/(x-2)(x+2)=1/(x+2)(x-2)
(=)1-x+3x+3=2x+3 (=)x^2+2x+x+2=1
(=)-x+3-2x=3-1-3 (=)x^2+3x+2=1
(=)0x=-1 (=)x^2+3x+2-1=0
=)S thuoc tap hop rong (=)x^2+3x+1=0
=) S thuoc tap hop rong
may tinh cua mk ko viet dc co dau nen bn thong cam nhe!