Đáp án:
$\displaystyle \begin{array}{{>{\displaystyle}l}} 2A.\\ a.\ A=2x\\ b.\ B=4\sqrt{x+1}\\ c.\ C=x\\ d\ D=\sqrt{a}\\ 2B.\\ a.\ A=-6\sqrt{x}\\ b.\ B=4\sqrt{x-1}\\ c.\ C=x\\ d.\ D=\sqrt{a} \end{array}$
Giải thích các bước giải:
$\displaystyle \begin{array}{{>{\displaystyle}l}} 2A.\\ a.\ A=4\sqrt{x} +2x-4\sqrt{x} =2x\\ b.\ B=5\sqrt{x+1} -3\sqrt{x+1} +2\sqrt{x+1} =4\sqrt{x+1}\\ c.\ C=\frac{x( x-1)}{x-1} =x\\ d\ D=\frac{\sqrt{a}\left(\sqrt{a} -1\right)}{\sqrt{a} -1} =\sqrt{a}\\ 2B.\\ a.\ A=2\sqrt{x} -3\sqrt{x} -5\sqrt{x} =-6\sqrt{x}\\ b.\ B=5\sqrt{x-1} -3\sqrt{x-1} +2\sqrt{x-1} =4\sqrt{x-1}\\ c.\ C=\frac{x( x-2)}{x-2} =x\\ d.\ D=\frac{\sqrt{a}\left(\sqrt{a} -2\right)}{\sqrt{a} -2} =\sqrt{a} \end{array}$
