Bài 15
a)
[tex]R=\frac{\frac{x^{2}-y^{2}}{x}}{\frac{y-x}{xy}}=\frac{x^{2}-y^{2}}{x}.\frac{xy}{y-x}=\frac{y(x^{2}-y^{2})}{y-x}=\frac{-y(y+x)(y-x))}{y-x}=-y(x+y)[/tex]
b)
[tex]S=\frac{\frac{x+x^{2}-x=y}{1+xy}}{1+\frac{x^{2}-xy}{1+xy}}=\frac{x^{2}y+y}{1+xy}.\frac{1+xy}{x^{2}-xy+1-xy}=\frac{x^{2}y+y}{1+xy}.\frac{1+xy}{x^{2}+1}=\frac{y(x^{2}+1)}{x^{2}+1}=y[/tex]
Bài 16
a)
[tex]\left\{\begin{matrix} 1-2x\neq 0\\ 1-x\neq 0\\ x+1\neq 0\\ 1-x^{2}\neq 0\\ x^{2}-1\neq 0 \end{matrix}\right.[/tex] [tex]\Rightarrow \left\{\begin{matrix} x\neq \frac{1}{2}\\ x\neq \pm 1 \end{matrix}\right.[/tex]
b)
[tex]P=\frac{1+x+1-x-5+x}{(1-x)(1+x)}.\frac{x^{2}-1}{1-2x}=\frac{x-3}{1-x^{2}}.\frac{-(1-x^{2})}{1-2x}=\frac{3-x}{1-2x}[/tex]
[TẶNG BẠN] TRỌN BỘ Bí kíp học tốt 08 môn
