Răspuns:
2.
[tex] \sqrt{21} (2 \sqrt{7} - \sqrt{75} ) + 3 \sqrt{21} (8 \sqrt{3} - \sqrt{7} )[/tex]
[tex] \sqrt{21} (2 \sqrt{7} - \sqrt{75} + 3(8 \sqrt{3} - 3 \sqrt{7} ))[/tex]
[tex] \sqrt{21} (2 \sqrt{7} - 10 \sqrt{3} + 24 \sqrt{3} - 9 \sqrt{7} [/tex]
[tex] \sqrt{21} ( - 7 \sqrt{7} + 14 \sqrt{3} )[/tex]
[tex] \sqrt{21} \times 7(2 \sqrt{3} - \sqrt{7} )[/tex]
[tex]7 \sqrt{21} (2 \sqrt{3} - \sqrt{7} )[/tex]
3.
[tex]0.2(6) = \frac{26 - 2}{90} = \frac{24}{90} = \frac{4}{15} [/tex]
[tex]0.(3) = \frac{3}{9} = \frac{1}{3} [/tex]
[tex] | \sqrt{ \frac{9}{5} \times \frac{4}{15} } - \sqrt{ \frac{9}{4} \times \frac{1}{3} } | \times 10 \sqrt{3} [/tex]
[tex] | \sqrt{ \frac{3}{5} \times \frac{4}{5} } - \sqrt{ \frac{3}{4} \times 1 } | \times 10 \sqrt{3} [/tex]
[tex] | \sqrt{ \frac{12}{25} } - \sqrt{ \frac{3}{4} } | \times 10 \sqrt{3} [/tex]
[tex]( \sqrt{ \frac{3}{4} } - \sqrt{ \frac{12}{25} } ) \times 10 \sqrt{3} [/tex]
[tex]10 \sqrt{ \frac{9}{4} } - 10 \sqrt{ \frac{36}{2} } [/tex]
[tex]10 \times \frac{3}{2} - 10 \frac{6}{5} [/tex]
[tex]5 \times 3 - 2 \times 6[/tex]
[tex]15 - 12[/tex]
[tex]3[/tex]
