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\(\frac{1717}{1212}x+\frac{1717}{2020}x+\frac{1717}{3030}x=\frac{17}{6}\)
=>\(\left(\frac{1717}{1212}+\frac{1717}{2020}+\frac{1717}{3030}\right)x=\frac{17}{6}\)
=>\(\frac{17}{6}x=\frac{17}{6}\)
=>x=1
\(\frac{1717}{1212}x+\frac{1717}{2020}x+\frac{1717}{3030}x=\frac{17}{6}\Rightarrow\left(\frac{17}{12}+\frac{17}{20}+\frac{17}{30}\right)x=\frac{17}{6}\Rightarrow\frac{17}{6}x=\frac{17}{6}\Rightarrow x=1\)
Ta có: \(\frac{\frac{3}{7}-\frac{3}{17}+\frac{3}{171}-\frac{3}{1717}}{\frac{9}{7}-\frac{9}{17}+\frac{9}{171}-\frac{9}{1717}}\)= \(\frac{3.\left(\frac{1}{7}-\frac{1}{17}+\frac{1}{171}-\frac{1}{1717}\right)}{9.\left(\frac{1}{7}-\frac{1}{17}+\frac{1}{171}-\frac{1}{1717}\right)}\)=\(\frac{3}{9}=\frac{1}{3}\)
B=(1-\(\frac{1}{2}\))x(1-\(\frac{1}{3}\))x(1-\(\frac{1}{4}\))x...x(1-\(\frac{1}{20}\))
B=\(\frac{1}{2}\)X\(\frac{2}{3}\)X\(\frac{3}{4}\)X...X\(\frac{19}{20}\)
B=\(\frac{1.2.3.4.4.5.7.8.9.10.11.12.13.14.15.16.17.18.19}{2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20}\)
B=20
Vậy B=20
Không biết kết quả đúng ko nhưng cách làm thì đúng.
B= \(\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{4}\right)x...x\left(1-\frac{1}{20}\right)\)
=\(\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.....\frac{19}{20}\)(Rút gọn cả tử xuống mẫu )
= \(\frac{1.2.3...19}{2.3.4...20}\)
=\(\frac{1}{20}\)
Vậy B= \(\frac{1}{20}\)
=>(\(\frac{7}{4}+\frac{21}{20}+\frac{7}{10}+\frac{1}{2}\))-x=-2015
=>(1,75+1,05+0,7+0,5)-x=-2015
=>4-x=-2015
=>x=4-(-2015)
=>x=2019
(\(\frac{2121}{1212}+\frac{2121}{2020}+\frac{2121}{3030}+\frac{2121}{4242}\)) - x = -2015
=> ( \(\frac{21}{12}+\frac{21}{20}+\frac{21}{30}+\frac{21}{42}\) ) - x = -2015
=> ( \(\frac{7}{4}+\frac{21}{20}+\frac{21}{30}+\frac{1}{2}\) ) - x = -2015
=> ( 1,75 + 1,05 + 0,7 + 0,5 ) - x = -2015
=> 4 - x = -2015
=> x = 4 - ( -2015 )
=> x = 4 + 2015
=> x = 2019
\(\left(\frac{2121}{1212}+\frac{2121}{2020}+\frac{2121}{3030}+\frac{2121}{4242}\right)-x=-2015\)
\(\left(\frac{21}{12}+\frac{21}{20}+\frac{21}{30}+\frac{1}{2}\right)=-2015+x\)
\(\left(\frac{7}{3}+\frac{21}{20}+\frac{7}{10}+\frac{1}{2}\right)=-2015+x\)
\(\left(\frac{140}{60}+\frac{63}{60}+\frac{42}{60}+\frac{30}{60}\right)=-2015+x\)
\(\frac{275}{60}=-2015+x\)
\(\frac{55}{12}+2015=x\)
\(x=\frac{55}{12}+\frac{24180}{12}\)
\(x=\frac{24235}{12}\)
\(\frac{121212}{171717}+\frac{2}{17}-\frac{40}{171}\)
\(=\frac{12}{17}+\frac{2}{17}-\frac{4}{17}=\frac{10}{17}\)
\(\Rightarrow A=B=\frac{10}{17}\)
121212/171717 + 2/7 - 40/171
= 12/17 + 2/7 - 4/17 = 10/17
= A = B = 10/17
Ta có:\(\frac{1717}{9999}\)=\(\frac{17}{99}\)
\(\frac{171717}{999999}\)=\(\frac{17}{99}\)
Vậy cả 3 phân số đó đều bằng nhau.
chúng đều bằng nhau vì:
1717/9999=17/99 và 171717/999999=17/99
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