Giải PT :
a) \(\sqrt{x^2+4x}+\sqrt{\frac{x^2}{2}-8}=0\)
b)\(\sqrt{2+x}+\sqrt{4x^2-6x-10}=0\)
c)\(x+\sqrt{x-5}+\sqrt{x}+\sqrt{x^2-5x}=20\)(Đặt t = \(\sqrt{x}+\sqrt{x-5}\), ĐK t \(\ge0\)
d)\(x^4-2x^2-12\sqrt{x^2+1}=12\)(Đặt t = \(\sqrt{x^2+1}\), ĐK t \(\ge1\))