= -15,5 .( 20,8 - 9,2) + 3,5 . (9,2+20,8)

=-15,5 . 11,6 + 3,5 .30

=-179,8+105

=-74,8

\(-15,5.20,8+3,5.9,2-15,5.9,2+3,5.20,8\)

\(=-15,5\left(20,8+9,2\right)+3,5\left(9,2+20,8\right)\)

\(=\left(9,2+20,8\right)\left(-15,5+3,5\right)\)

\(=30.\left(-12\right)=-360\)

\(-15,5\times20,8+3,5\times9,2-15,5\times9,2+3,5\times20,8.\)

\(=20,8\times\left(3,5-15,5\right)+9,2\times\left(3,5-15,5\right)\)

\(=\left(3,5-15,5\right)\times\left(20,8+9,2\right)\)

\(=\left(-12\right)\times30\)

\(=-360\)

 -15,5 x 20,8 + 3,5 x 9,2- 15,5 x 9,2 + 3,5 x 20,8=-360

k mk nha mn 

=-360 nha pạn

\(-15,5.20,8+3,5.9,2-15,5.9,2+3,5.20,8\)

\(=-15,5\left(20,8+9,2\right)+3,5\left(9,2+20,8\right)\)

\(=\left(-15,5\right).30+3,5.30\)

\(=30.\left(-12,5\right)\)

\(=-375\)

\(-15,5.20,8+3,5.9,2-15,5.9,2+3,5.20,8\)

\(=20,8.\left(-15,5+3,5\right)+9,2.\left(-15,5+3,5\right)\)

\(=\left(-15,5+3,5\right).\left(20,8+9,2\right)\)

\(=\left(-12\right).30\)

\(=-360\)

Vậy : \(-15,5.20,8+3,5.9,2-15,5.9,2+3,5.20,8=-360\)

\(-15,5.20,8+3,5.9,2-15,5.9,2+3,5.20,8\)

= \(20,8.\left(-15,5+3,5\right)+9,2.\left(-15,5+3,5\right)\)

= \(20,8.\left(-12\right)+9,2.\left(-12\right)\)

= \(\left(20,8+9,2\right).\left(-12\right)\)

= \(30.\left(-12\right)\)

= \(-360.\)

Chúc bạn học tốt!

A) -15,5 x 20,8 +2,5 x 9,2 -15,5 x 9,2 + 3,5 x 20,8

=-15,5 x 20,8 + 2,5 x 9,2 + -15,5 x 9,2 +3,5 x 20,8

=[20,8x(-15,5+3,5)]+[9,2x(2,5+-15,5)]

=[20,8x(-12)]+[9,2x(-13)]

=-249,6+-119,6

=-369,2

a) -369,2

b) -7

B)(-3/4+5/13):2/7-(9/4-8/13):2/7

=(-19/52-85/52):2/7

=-2:2/7

=-7

a) \(1\dfrac{7}{20}:2,7+2,7:1,35+\left(0,4:2\dfrac{1}{2}\right).\left(4,2-1\dfrac{3}{40}\right)\)

\(=\dfrac{27}{20}:\dfrac{27}{10}+\dfrac{27}{10}:\dfrac{27}{10}+\left(\dfrac{2}{5}:\dfrac{5}{2}\right).\left(\dfrac{21}{5}-\dfrac{43}{40}\right)\)

\(=1+1+\dfrac{4}{25}.\dfrac{25}{8}\)

\(=2+\dfrac{1}{2}\)

\(=2\dfrac{1}{2}\)

b) \(\left(6\dfrac{3}{5}-3\dfrac{3}{14}\right).5\dfrac{5}{6}:\left(21-1.25\right):2,5\)

\(=\left(\dfrac{33}{5}-\dfrac{45}{14}\right).\dfrac{35}{6}:\left(-4\right):2,5\)

\(=\left(\dfrac{462}{60}-\dfrac{225}{60}\right).\dfrac{35}{6}.\dfrac{1}{-4}:\dfrac{5}{2}\)

\(=\dfrac{237}{60}.\dfrac{35}{6}.\dfrac{1}{-4}.\dfrac{2}{5}\)

\(=\dfrac{3.79.7.5.2}{5.14.3.2.\left(-4\right).5}\)

\(=\dfrac{79.7}{14.\left(-4\right).5}=\dfrac{553}{-280}\) (số xấu :v)

c) \(\dfrac{0,125-\dfrac{1}{5}+\dfrac{1}{7}}{0,375-\dfrac{3}{5}+\dfrac{3}{7}}+\dfrac{\dfrac{1}{2}+\dfrac{1}{3}-0,2}{\dfrac{3}{4}+0,5-\dfrac{3}{10}}\)

\(=\dfrac{0,125-\dfrac{1}{5}+\dfrac{1}{7}}{3\left(0,125-\dfrac{1}{5}+\dfrac{1}{7}\right)}+\dfrac{\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{5}}{\dfrac{3}{4}+\dfrac{1}{2}-\dfrac{3}{10}}\)

\(=\dfrac{1}{3}+\dfrac{\dfrac{30}{60}+\dfrac{20}{60}-\dfrac{12}{60}}{\dfrac{45}{60}+\dfrac{30}{60}-\dfrac{9}{60}}\)

\(=\dfrac{1}{3}+\dfrac{\dfrac{19}{30}}{\dfrac{11}{10}}\)

\(=\dfrac{1}{3}+\dfrac{19}{33}\)

\(=\dfrac{11}{33}+\dfrac{19}{33}=\dfrac{30}{33}=\dfrac{10}{11}\)

1207​:2,7+2,7:1,35+(0,4:212221​).(4,2-13401403​^₎=

   \(1\dfrac{7}{20}\div2,7+2,7\div1,35+\left(0,4\div2\dfrac{1}{2}\right)\times\left(4,2-1\dfrac{3}{40}\right)\)

\(=\dfrac{27}{20}\div\dfrac{27}{10}+\dfrac{27}{10}\div\dfrac{27}{20}+\left(\dfrac{2}{5}\div\dfrac{5}{2}\right)\times\left(\dfrac{21}{5}-\dfrac{43}{40}\right)\)

\(=\dfrac{27}{20}\times\dfrac{10}{27}+\dfrac{27}{10}\times\dfrac{20}{27}+\left(\dfrac{2}{5}\times\dfrac{2}{5}\right)\times\dfrac{25}{8}\)

\(=\dfrac{1}{2}+2+\dfrac{4}{25}\times\dfrac{25}{8}\)

\(=\dfrac{5}{2}+\dfrac{1}{2}\)

\(=3\)