Question

[Lê khắc Tuấn Minh]

Giải các phương trình sau

a) \(-x^2+4\cdot x+1=2\cdot\sqrt{2\cdot x+1}\)

b) \(x+\sqrt{x+\dfrac{1}{2}+\sqrt{x+\dfrac{1}{4}}}=2\)

c) \(5\cdot x^2-2\cdot x+1=\left(4\cdot x-1\right)\cdot\sqrt{x^2+1}\)

d) \(\left(2\cdot x-1\right)\cdot\sqrt{10-4\cdot x^2}=5-2\cdot x\)

e) \(\sqrt{2\cdot x-1}-\sqrt{x+1}=2\cdot x-4\)

f) \(\sqrt{x^2-2\cdot x}+\sqrt{2\cdot x^2+4\cdot x}=2\cdot x\)

Answer 1

[ngonhuminh]

câu b đk x>= -1/4

\(x+\sqrt{x+\dfrac{1}{2}+\sqrt{x+\dfrac{1}{4}}}=2\)

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

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

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

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

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

\(x=\sqrt{2}\left(\sqrt{2}-1\right)=2-\sqrt{2}\)

Answer 2

[Lê khắc Tuấn Minh]

bạn ghi cai gì vậy hả. Mình chẳng hiểu gì hết ý