Bài 1:
a: \(\sqrt{\frac{16}{25}}=\frac{\sqrt{16}}{\sqrt{25}}=\frac45\)
b: \(\sqrt{\frac{0.4}{0.9}}=\sqrt{\frac49}=\frac23\)
c: \(\sqrt{\frac{25}{4}:\frac14}=\sqrt{25}=5\)
d: \(\sqrt{\frac{25}{2}:\frac92}=\sqrt{\frac{25}{9}}=\frac{\sqrt{25}}{\sqrt9}=\frac53\)
Bài 2:
a: \(\sqrt{x}:\sqrt{\frac{x}{9}}=\sqrt{x:\frac{x}{9}}=\sqrt9=3\)
b: \(\sqrt{-\frac{4}{y}}:\sqrt{\frac{y^3}{-9}}=\sqrt{-\frac{4}{y}:\frac{y^3}{-9}}=\sqrt{\frac{36}{y^4}}=\frac{6}{y^2}\)
c: \(\sqrt{-\frac{1}{3x}}:\sqrt{-27x^7}=\sqrt{\frac{1}{3x}:27x^7}=\sqrt{\frac{1}{81x^8}}=\frac{1}{9x^4}\)
d: \(\sqrt{\frac{x^2}{3}}:\sqrt{\frac{27}{x^6}}=\sqrt{\frac{x^2}{3}:\frac{27}{x^6}}=\sqrt{\frac{x^8}{81}}=\frac{x^4}{9}\)
Bài 3:
a: ĐKXĐ: \(\frac{2x-1}{x+1}\ge0\)
=>x>=1/2 hoặc x<-1
\(\sqrt{\frac{2x-1}{x+1}}=1\)
=>\(\frac{2x-1}{x+1}=1\)
=>2x-1=x+1
=>x=2(nhận)
b: ĐKXĐ: x>=1
\(\frac{\sqrt{x-1}}{\sqrt{x+1}}=2\)
=>\(\sqrt{\frac{x-1}{x+1}}=2\)
=>\(\frac{x-1}{x+1}=4\)
=>4(x+1)=x-1
=>4x+4=x-1
=>3x=-5
=>x=-5/3(loại)
