100

\(\dfrac{9}{14}-\dfrac{5}{8}+\dfrac{3}{7}\)

\(=\dfrac{36}{56}-\dfrac{35}{56}+\dfrac{24}{56}\)

\(=\dfrac{25}{56}\)

____________________

\(\dfrac{2}{9}-\dfrac{7}{10}+\dfrac{4}{5}\)

\(=\dfrac{20}{90}-\dfrac{63}{90}+\dfrac{72}{90}\)

\(=\dfrac{29}{90}\)

____________________

\(\dfrac{8}{19}+\dfrac{7}{5}-\dfrac{9}{20}+\dfrac{11}{12}\)

\(=\dfrac{173}{95}-\dfrac{9}{20}+\dfrac{11}{12}\)

\(=\dfrac{521}{380}+\dfrac{11}{12}\)

\(=\dfrac{652}{285}\)

\(\dfrac{-11}{12}+\dfrac{7}{8}+\dfrac{1}{10}\)

\(=\dfrac{-22}{24}+\dfrac{21}{24}+\dfrac{1}{10}\)

\(=\dfrac{-1}{24}+\dfrac{1}{10}\)

\(=\dfrac{-5}{120}+\dfrac{12}{120}\)

\(=\dfrac{7}{120}\)

Đề là 174 mà e cho xuống lại là 175 à. Nếu là 175 thì dòng 3 sai, và kq của e cũng sai vậy. Kiểm tra lại câu tl nhé

Xem kĩ lại đề nha bnn.

1 con gấu là: 36 : 3 = 12

1 cái bánh là: ( 26 - 12 ) : 2 = 7

1 Chùm nho là : (15 - 7 ) : 2 = 4

1 con gấu - 1 cái bánh + 1chùm nho

hay: 12 - 7 + 4 = 9

\(91-3.\left(7+x\right)=64\)

\(3.\left(7+x\right)=91-64\)

\(3.\left(7+x\right)=27\)

\(7+x=27:3\)

\(7+x=9\)

\(x=9-7\)

\(x=2\)

\(\dfrac{1}{1}-\dfrac{5}{100}\)

\(=\dfrac{100}{100}-\dfrac{5}{100}\)

\(=\dfrac{95}{100}=\dfrac{19}{20}\)

Thêm: 

\(3A=\left(3^{3008}-3\right):2\)

1) Tính 

\(A=1+3+3^2+...+3^{2006}\)

\(3A=3\times\left(1+3+3^2+...+3^{2006}\right)\)

\(3A=3+3^2+3^3+...+3^{2007}\)

\(3A-A=\left(3+3^2+3^3+...+3^{2007}\right)-\left(1+3+3^2+...+3^{2006}\right)\)

\(2A=3^{2007}-1\)

\(A=\left(3^{2007}-1\right):2\)