Đáp án:
Giải thích các bước giải:
D=x2+4x+42x+4=(x+2)22(x+2)=x+22a;c.D=x2+4x+42x+4=(x+2)22(x+2)=x+22 ( x # - 2)
E=2x−x2x2−4=−x(x−2)(x+2)(x−2)=−xx+2E=2x−x2x2−4=−x(x−2)(x+2)(x−2)=−xx+2 ( x # 2 ; x # - 2)
F=3x2+6x+12x2−8=3(x2+2x+4)(x−2)(x2+2x+4)=3x−2F=3x2+6x+12x2−8=3(x2+2x+4)(x−2)(x2+2x+4)=3x−2 ( x #2)
b.D=x+22=0b.D=x+22=0 ⇔ x=−2(KTM)x=−2(KTM)
E=−xx+2=0E=−xx+2=0 ⇔ x = 0 ( TM)
F=3x−2=0F=3x−2=0 ⇔ Vô nghiệm .