\(\dfrac{19}{15}\times\dfrac{23}{14}\times\dfrac{15}{19}=\dfrac{19}{19}\times\dfrac{15}{15}\times\dfrac{23}{14}=\dfrac{23}{14}\)

\(\dfrac{x-1}{2023}-\dfrac{1}{10}-\dfrac{1}{15}-\dfrac{1}{21}-...-\dfrac{1}{120}=\dfrac{5}{8}\)

=>\(\dfrac{x-1}{2023}-\left(\dfrac{1}{10}+\dfrac{1}{15}+...+\dfrac{1}{120}\right)=\dfrac{5}{8}\)

=>\(\dfrac{x-1}{2023}-2\left(\dfrac{1}{20}+\dfrac{1}{30}+...+\dfrac{1}{240}\right)=\dfrac{5}{8}\)

=>\(\dfrac{x-1}{2023}-2\left(\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+...+\dfrac{1}{15}-\dfrac{1}{16}\right)=\dfrac{5}{8}\)

=>\(\dfrac{x-1}{2023}-2\left(\dfrac{1}{4}-\dfrac{1}{16}\right)=\dfrac{5}{8}\)

=>\(\dfrac{x-1}{2023}-2\cdot\dfrac{3}{16}=\dfrac{5}{8}\)

=>\(\dfrac{x-1}{2023}=\dfrac{5}{8}+\dfrac{3}{8}=\dfrac{8}{8}=1\)

=>x-1=2023

=>x=2024

\(x\) + \(\frac{35}{56}\) = \(\frac78\)

\(x\) = \(\frac78\) - \(\frac{35}{56}\)

\(x\) = \(\frac{49}{56}\) - \(\frac{35}{56}\)

\(x\) = \(\frac{14}{56}\)

\(x=\frac14\)

a: \(\dfrac{32\times50}{48\times25}=\dfrac{32}{48}\times\dfrac{50}{25}=\dfrac{2}{3}\times2=\dfrac{4}{3}\)

b: \(\dfrac{56\times27}{49\times36}=\dfrac{56}{49}\times\dfrac{27}{36}=\dfrac{8}{7}\times\dfrac{3}{4}=\dfrac{3\times2}{7}=\dfrac{6}{7}\)

c: \(\dfrac{121\times42}{77\times54}=\dfrac{121}{77}\times\dfrac{42}{54}=\dfrac{11}{7}\times\dfrac{7}{9}=\dfrac{11}{9}\)

a: \(56\times89-46\times89\)

\(=89\times\left(56-46\right)\)

\(=89\times10=890\)

b: 700+197-200+203

=500+(197+203)

=500+400

=900

a) 56 x 89 - 46 x 89

= (56 x 89 - 46 x 8)

= (56 - 46) x 89

= 10 x 89

= 890

b) 700 + 197 - 200 + 203

= (700 - 200) + (197 + 203)

= 500 + 400

= 900

Tick cho tớ với ạ

Giải:

Thời gian mà bác Minh cần trở lại làng:

9 : 1,5 = 6(giờ)

Đáp số: 6 giờ

-16 x (-0,125) x (-0,5)

= 2 x (-0,5)

= - 1

=-1 nha

A = 2 - 3 - 4 + 5 + 6 - 7 - 8 + 9 + ... + 2018 - 2019 - 2020

Xét dãy số: 2; 3; 4;...; 2019; 2020

Dãy số trên có số số hạng là:

(2020 - 2) : 1 + 1 = 2019

Vì 2019 : 4 = 504 dư 3

Nhóm 4 số hạng liên tiếp của A vào nhau khi đó:

A = (2-3-4+5)+(6-7-8+9)+ ...+(2014 - 2015 - 2016+2017) + (2018 - 2019 - 2020)

A = 0 + 0 + ...+ 0 + (-1 - 2020)

A = - 2021

\(x\) = 3 + 9 + 3

\(x\) = 12 + 3

\(x=15\)

x = 15

A = \(\frac13\) + \(\frac16\) + \(\frac{1}{10}\) + \(\frac{1}{15}\) + ... + \(\frac{1}{45}\)

A = \(\frac26\) + \(\frac{2}{12}\) + \(\frac{2}{20}\) + \(\frac{2}{30}\) + ... + \(\frac{2}{90}\)

A = 2.(\(\frac{1}{2.3}\) + \(\frac{1}{3.4}\) + \(\frac{1}{4.5}\) + ... + \(\frac{1}{9.10}\))

A = 2.(\(\frac12-\frac13\) + \(\frac13-\frac14\) +\(\frac14-\) \(\frac15\) + ... + \(\frac19\) - \(\frac{1}{10}\))

A = 2.(\(\frac12-\frac{1}{10}\))

A = 2.\(\frac25\)

A = \(\frac45\)