a) $\sqrt{3x-2}=2-\sqrt3$
ĐK: $3x-2\ge0\Rightarrow x\ge\dfrac{2}{3}$
Phương trình suy ra:
$3x-2=4-4\sqrt3+3$
$\Rightarrow x=\dfrac{9-4\sqrt3}{3}$ (tm)
b) $\sqrt[3]{x-5}=0,9$
$\Rightarrow x-5=0,9^3$
$\Rightarrow x=0,725+5$
$\Rightarrow x=5,725$
c) $\sqrt{4x+20} - 3 \sqrt{5+x} + \dfrac{4}{3}\sqrt {9x+45}=6$ ĐK: $x\ge-5$
$\Rightarrow 2\sqrt{x+5}-3\sqrt{x+5}+\dfrac{4}{3}.3\sqrt{x+5}=6$
$\Rightarrow 3\sqrt{x+5}=6$
$\Rightarrow x+5=2^2$
$\Rightarrow x=-1$ (tm)