Cho biểu thức: B = x^2 + 2x/ 2x +10 + x- 5/ x + 50 - 5x/ 2x(x+5)

a) x≠0, x≠−5

b) B=x2+2x2x+10+x−5x+50−5x2xx+5=xx+22x+5+x−5x+50−5x2xx+5=x3+2x2+x−5x+5+50−5x2xx+5=x3+3x2−5x+252xx+5=x2(x+5)−2x(x+5)+5(x+5)2xx+5=x+5x2−2x+52xx+5=x2−2x+52x

B=0⇔x2−2x+52x=0⇔x2−2x+5=0 (vô lý vì x2−2x+5=(x−1)2+4>0)

B=14⇔x2−2x+52x=14⇔4x2−10x+20=0(VN)