Question

[Na]

Giải phương trình

a) \(\sqrt{12x^2+12x+19}+\sqrt{20x^2+20x+14}=6-4x-4x^2\)

b) \(\left(x+\dfrac{1}{x}\right)-4\left(\sqrt{x}+\dfrac{1}{\sqrt{x}}\right)+6=0\)

Answer 1

[Nguyễn Lê Phước Thịnh]

b:

ĐKXĐ: x>0

 \(\Leftrightarrow\left(\sqrt{x}+\dfrac{1}{\sqrt{x}}\right)^2-2-4\left(\sqrt{x}+\dfrac{1}{\sqrt{x}}\right)+6=0\)

\(\Leftrightarrow\left(\sqrt{x}+\dfrac{1}{\sqrt{x}}-2\right)^2=0\)

\(\Leftrightarrow x+1-2\sqrt{x}=0\)

=>x=1