Question

Rezultatul calcului 3×[0,(3) + 0,2(6)]
Media aritmetica a nr a=radical 125-3 radical 20
b=3 radical 5+ radical 80

Answer 1

3 × [ 0,(3) + 0,2(6) ] = 1,8

= 3 × [ 3 / 9 + ( 26 - 2) / 90 ]=

= 3 × ( 1 / 3 + 24 / 90 )=

= 3 ×( 1 / 3 + 4 / 15 ) =

= 3 × ( 5 / 15 + 4 / 15 ) =

= 3 × 9 /15 =

= 9 / 5 =

= 1 intreg si 4 / 5 = 1,8

a = √125 - 3√20 = 5√5 - 3×2√5= 5√5 - 6√5 = - √5

b = 3√5 + √80 = 3√5 + 4√5 = 7√5

Ma = ( - √5 + 7√5 ) / 2 = 6√5 / 2 = 3√5

Answer 2

$\displaystyle\\ 1)\\ 3\times[0,\!3+0,\!2(6)]=\\\\ =3\times\Big[\frac{3}{9}+\frac{26-2}{90}\Big]=\\\\ =3\times\Big[\frac{30}{90}+\frac{24}{90}\Big]=\\\\ =3\times \frac{30+24}{90}=\\\\ = \frac{3\times54}{90}=\frac{3\times 6}{10}=\frac{18}{10}=\boxed{\bf1,\!8}\\\\ 2)\\ a=\sqrt{125}-3 \sqrt{20}=5\sqrt{5}-3\times2\sqrt{5}=5\sqrt{5}-6\sqrt{5}=\boxed{-\sqrt{5}} \\\\ b=3\sqrt{5}+\sqrt{80}=3\sqrt{5}+4\sqrt{5}=\boxed{7\sqrt{5}}\\\\ m_a=\frac{a+b}{2}=\frac{-\sqrt{5}+7\sqrt{5}}{2}=\frac{6\sqrt{5}}{2}=\boxed{3\sqrt{5}}$