Giải các PT sau:
3) $\sqrt[3]{x+1}+\sqrt[3]{3x+1}=\sqrt[3]{x-1}$
4) $\sqrt{2x+1}+\sqrt{3-2x}=\frac{\left ( 2x-1 \right )^{2}}{2}$
5) $\sqrt{1-2x}+\sqrt{1+2x}=2-x^{2}$
3.
đặt $\sqrt[3]{x-1}=a; \sqrt[3]{x+1}=b\Rightarrow a+\sqrt[3]{2a^3+b^3}=b$
$\Leftrightarrow (a-b)^3=2a^3+b^3$
$\Leftrightarrow 3a(a^2-ab+b^2)=0$
4.
đk:...
$\sqrt{1+2x}+\sqrt{3-2x}\geq \sqrt{1+2x+3-2x}=2\Rightarrow (2x-1)^2\geq 4\Rightarrow x\geq \frac{3}{2}hoac x\leq \frac{-1}{2}$
kết hợp đk => no
5.
đk:...
$\Rightarrow 2+2\sqrt{1-4x^2}=(2-x^2)^2$
$\Rightarrow (\sqrt{1-4x^2}-1)^2+x^4=0$
$\Rightarrow x=0$