a) Ta có:
\(\sqrt{\dfrac{289}{225}}=\dfrac{\sqrt{289}}{\sqrt{225}}=\dfrac{\sqrt {17^2}}{\sqrt{15^2}}=\dfrac{17}{15}\).
b) Ta có:
\(\sqrt{2\dfrac{14}{25}}=\sqrt{\dfrac{2.25+14}{25}}=\sqrt{\dfrac{50+14}{25}}\)
\(=\sqrt{\dfrac{64}{25}}=\dfrac{\sqrt{64}}{\sqrt{25}}=\dfrac{\sqrt{8^2}}{\sqrt{5^2}}=\dfrac{8}{5}\).
c) Ta có:
\(\sqrt{\dfrac{0,25}{9}}=\dfrac{\sqrt{0,25}}{\sqrt{9}}=\dfrac{\sqrt{0,5^2}}{\sqrt{3^2}}=\dfrac{0,5}{3}\)
\(=0,5.\dfrac{1}{3}=\dfrac{1}{2}.\dfrac{1}{3}=\dfrac{1}{6}\).
d) Ta có:
\(\sqrt{\dfrac{8,1}{1,6}}=\sqrt{\dfrac{81.0,1}{16.0,1}}=\sqrt{\dfrac{81}{16}}=\dfrac{\sqrt{81}}{\sqrt{16}}=\dfrac{\sqrt{9^2}}{\sqrt{4^2}}=\dfrac{9}{4}\).
