Question

Bài 2: Giải phương trình:

a) \(3\sqrt{x}-1=8\)

b) \(\sqrt{x^2-6x+9}=\left|-2\right|\)

c) \(2\sqrt{9\left(x-3\right)}-\dfrac{1}{2}\sqrt{25\left(x-3\right)}+\dfrac{1}{7}\sqrt{49\left(x-3\right)}=20\)

d) \(2x+\sqrt{2x+19}=1\)

Answer 1

a) \(3\sqrt{x}-1=8< =>3\sqrt{x}=9< =>x=9\left(TM\right)\)
b) \(< =>\sqrt{x^2-2x.3+3^2}=2< =>\left|x-3\right|=2< =>\left\{{}\begin{matrix}x=5\\x=1\end{matrix}\right.\)
c) \(< =>2.3\sqrt{x-3}-\dfrac{1}{5}.5\sqrt{x-3}+\dfrac{1}{7}.7\sqrt{x-3}=20< =>\sqrt{x-3}=\dfrac{20}{6}< =>x=\dfrac{127}{9}\)
d) \(< =>\left(\sqrt{2x}+19\right)^2=\left(1-2x\right)^2,=>2x^2-3x-9=0< =>2x\left(x-3\right)+3\left(x-3\right)=0\)
\(< =>\left(2x+3\right)\left(x-3\right)=0< =>\left[{}\begin{matrix}x=\dfrac{-3}{2}\left(TM\right)\\x=3\left(loại\right)\end{matrix}\right.\)