\(\left(\frac{2121}{1212}+\frac{2121}{2020}+\frac{2121}{3030}+\frac{2121}{4242}\right)-x=-2015\)

\(\left(\frac{21}{12}+\frac{21}{20}+\frac{21}{30}+\frac{1}{2}\right)=-2015+x\)

\(\left(\frac{7}{3}+\frac{21}{20}+\frac{7}{10}+\frac{1}{2}\right)=-2015+x\)

\(\left(\frac{140}{60}+\frac{63}{60}+\frac{42}{60}+\frac{30}{60}\right)=-2015+x\)

\(\frac{275}{60}=-2015+x\)

\(\frac{55}{12}+2015=x\)

\(x=\frac{55}{12}+\frac{24180}{12}\)

\(x=\frac{24235}{12}\)

giúp j bạn bài có yêu cầu mình làm cái j đâu mà jup

Ai làm đúng và nhanh nhất mk k cho

cái thứ hai lớn hơn

Ta có : \(\frac{1212+1313+1414+1515+1616}{1717+1818+1919+2020+2121}=\frac{12+13+14+15+16}{17+18+19+20+21}=\frac{28\cdot\frac{5}{2}}{38\cdot\frac{5}{2}}=\frac{14}{19}\)

Dễ thấy \(\frac{111111}{666665}< \frac{1}{2}\) ( do 111111 < 666665/2 ) và \(\frac{14}{19}>\frac{1}{2}\) ( do 14 > 19/2 )

Vậy \(\frac{111111}{666665}< \frac{1212+1313+1414+1515+1616}{1717+1818+1919+2020+2121}\)

1212+2121+4242+2424

=1212+2121+2121+2121+1212+1212

=(1212+2121)+(2121+1212)+(1212+2121)

=3333+3333+3333

=3333 x 3 =9999

1212+2121+4242+2424=

=3333+6666

=9999

\(\frac{242}{363}+\frac{1616}{2121}=\frac{2}{7}.\frac{2015}{A}\)

\(\frac{11.11.2}{11.11.3}+\frac{101.16}{101.21}=\frac{2}{7}.\frac{2015}{A}\)

\(\frac{2}{3}+\frac{16}{21}=\frac{2}{7}.\frac{2015}{A}\)

\(\Rightarrow\frac{2}{7}.\frac{2015}{A}=\frac{10}{7}\)

\(\frac{2015}{A}=\frac{10}{7}:\frac{2}{7}\)

\(\frac{2015}{A}=5\)

\(A=2015:5\)

\(A=403\)

\(\left(\frac{242}{363}+\frac{1616}{2121}\right)=\frac{2}{7}.\frac{2015}{A}\)

\(\Leftrightarrow\left(\frac{2}{3}+\frac{16}{21}\right)=\frac{2}{7}.\frac{2015}{A}\)

\(\Leftrightarrow\frac{10}{7}=\frac{2}{7}.\frac{2015}{A}\)

\(\Leftrightarrow5=\frac{2015}{A}\)

\(\Leftrightarrow A=403\)

10/7 = 2/7 . 2015/A

2015/A = 10/7 / 2/7 = 5

2015/A = 5/1

A = 2015 / 5 = 403

\(\frac{1414+1515+1616+1717+1818+1919}{2020+2121+2222+2323+2424+2525}=\frac{9999}{13635}=\frac{11}{15}\)

18 x \(\left(\frac{1919}{2121}+\frac{888}{999}\right)\)

= 18 x \(\frac{113}{63}\)

= \(\frac{226}{7}\)

Đây có phải tính nhanh không bạn?

\(18\cdot\left(\frac{1919}{2121}+\frac{888}{999}\right)\)

Rút gọn:

\(\frac{1919}{2121}=\frac{1919:101}{2121:101}=\frac{19}{21}\)

\(\frac{888}{999}=\frac{888:111}{999:111}=\frac{8}{9}\)

Ta có:

\(18\cdot\left(\frac{19}{21}+\frac{8}{9}\right)\)

=\(18\cdot\left(\frac{57}{63}+\frac{56}{63}\right)\)

\(=18\cdot\frac{113}{63}\)

\(\frac{18.113}{63}=\frac{9\cdot2\cdot113}{9\cdot7}=\frac{2\cdot113}{7}=\frac{226}{7}\)

Kết quả là \(\frac{226}{7}\)

Đúng thì tk nha!!!

\(\frac{2323+1313+1414+1515+1616}{4141+2222+2323+2424+2525}\)

=\(\frac{8181}{13635}\)

18180,8               

\(\frac{1414+1515+1616+1717+1818+1919}{2020+2121+2222+2323+2424+2525}\)

\(=\frac{101\times\left(14+15+16+17+18+19\right)}{101\times\left(20+21+22+23+24+25\right)}\)

\(=\frac{14+15+16+17+18+19}{20+21+22+23+24+25}\)

+) Tử số :

Số các số hạng là : ( 19 - 14 ) : 1 + 1 = 6 ( số )

Tổng là : ( 19 + 14 ) x 6 : 2 = 99

+) Mẫu số :

Số các số hạng là : ( 25 - 20 ) : 1 + 1 = 6 ( số )

Tổng là : ( 25 + 20 ) x 6 : 2 = 135

\(\Leftrightarrow\frac{99}{135}=\frac{11}{15}\)

\(\frac{1010+1111+1212+1313+1414+1515+1616+1717}{2020+2121+2222+2323+2424+2525+2626+2727}\)

\(=\frac{101.10+101.11+...+101.17}{101.20+101.21+...+101.27}\)

\(=\frac{101.\left(10+11+...+17\right)}{101.\left(20+21+...+27\right)}\)

\(=\frac{108}{188}\)

\(=\frac{27}{47}\)

\(2>\left(\frac{1}{6}+\frac{2}{15}+\frac{3}{40}+\frac{4}{96}\right)\cdot5.y>\frac{5}{6}\)

\(\Rightarrow2>\left(\frac{1}{6}+\frac{2}{15}+\frac{3}{40}+\frac{1}{24}\right):5.y>\frac{5}{6}\)

\(\Rightarrow2>\left(\frac{20}{120}+\frac{16}{120}+\frac{9}{120}+\frac{5}{120}\right):5.y>\frac{5}{6}\)

\(\Rightarrow2>\frac{5}{12}:5.y>\frac{5}{6}\)

\(\Rightarrow2>\frac{1}{12}.y>\frac{5}{6}\)

Đặt :\(\frac{1}{12}.y=2\Rightarrow y=2:\frac{1}{12}=24\)

\(\frac{1}{12}.y=\frac{5}{6}\Rightarrow y=\frac{5}{6}:\frac{1}{12}=10\)

\(\Rightarrow24>y>10\)

\(\Rightarrow y\in\left\{11;12;...;23\right\}\)

ko biết

I am sorry

Kb nhé