Question

Tính:

a) \(\sqrt{\dfrac{0,49}{81}}\);              b) \(\sqrt{2\dfrac{7}{9}}\);                 c) \(\sqrt{\dfrac{1}{16}.\dfrac{9}{36}}\);                 d) \(\left(-\sqrt{52}\right):\sqrt{13}\).

Answer 1

a) \(\sqrt {\frac{{0,49}}{{81}}}  = \frac{{\sqrt {0,49} }}{{\sqrt {81} }} = \frac{{0,7}}{9} = \frac{7}{{90}}\)

b) \(\sqrt {2\frac{7}{9}}  = \sqrt {\frac{{25}}{9}}  = \frac{{\sqrt {25} }}{{\sqrt 9 }} = \frac{5}{3}\)

c) \(\sqrt {\frac{1}{{16}}.\frac{9}{{36}}}  = \sqrt {\frac{1}{{16}}} .\sqrt {\frac{9}{{36}}}  = \frac{1}{4}.\frac{{\sqrt 9 }}{{\sqrt {36} }} = \frac{1}{4}.\frac{3}{6} = \frac{3}{{24}} = \frac{1}{8}\)

d) \(\left( { - \sqrt {52} } \right):\sqrt {13}  =  - \frac{{\sqrt {52} }}{{\sqrt {13} }} =  - \sqrt {\frac{{52}}{{13}}}  =  - \sqrt 4  =  - 2\)