Cho biểu thức A=[(xcănx+1)/(cănx-1)(căn x+1)-(x-1)/(căn x-1]:(căn x+ căn x/ cănx -1)
Giải thích
A=xx+1x−1x+1−x−1x−1:x+xx−1 =x3+1x−1x+1−x−1x+1x−1:x−x+xx−1 =x+1x−x+1x−1x+1−x−1.x−1x=x−x+1x−1+x−1x−1.x−1x=x−x+1+x−1x−1.x−1x=x−x+1+x−1x−1.x−1x=2x−xx=2x−1x
b. A=3⇔2x−1x=3⇔x−1=3x⇔x=−1