Tìm giới hạn B= lim(x_>2) (x^4-5x^2+4)/(x^3-8)
Giải thích
Chọn D
B=limx→2x4−5x2+4x3−8=limx→2(x2−1)(x2−4)x3−23
=limx→2(x2−1)(x−2)(x+2)(x−2)(x2+2x+4)
=limx→2(x2−1)(x+2)x2+2x+4=(22−1).(2+2)22+2.2+4=1
Chọn D
B=limx→2x4−5x2+4x3−8=limx→2(x2−1)(x2−4)x3−23
=limx→2(x2−1)(x−2)(x+2)(x−2)(x2+2x+4)
=limx→2(x2−1)(x+2)x2+2x+4=(22−1).(2+2)22+2.2+4=1