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\(\frac{1}{1\times2}+\frac{1}{2\times3}+\frac{1}{3\times4}+...+\frac{1}{y\times\left(y+1\right)}=\frac{996}{997}\)
\(\Leftrightarrow1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{y}-\frac{1}{y+1}=\frac{996}{997}\)
\(\Leftrightarrow1-\frac{1}{y+1}=\frac{996}{997}\)
\(\Leftrightarrow\frac{1}{y+1}=1-\frac{996}{997}=\frac{1}{997}\)
\(\Leftrightarrow y+1=997\Leftrightarrow y=996\)
Vậy y = 996
\(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\)
\(=\frac{81}{243}+\frac{27}{243}+\frac{9}{243}+\frac{3}{243}+\frac{1}{243}\)
\(=\frac{121}{243}\)
mk ko bít đúng hay ko nữa có gì mấy bạn góp ý cho mình nhé ! Thanks
\(x+x\times\frac{1}{3}:\frac{2}{9}+x:\frac{2}{7}=252\)
\(x+x\times\frac{3}{2}+x\times\frac{7}{2}=252\)
\(x\times\left(1+\frac{3}{2}+\frac{7}{2}\right)=252\)
\(x\times6=252\)
\(x=252:6\)
\(x=42\)
X + X x \(\frac{1}{3}\)x\(\frac{9}{2}\)+ X x\(\frac{7}{2}\)= 252
X + X x \(\frac{3}{2}\)+ X x \(\frac{7}{2}\)= 252
X x (\(\frac{3}{2}\)+ \(\frac{7}{2}\)+1) = 252
X x (\(\frac{3}{2}\)+ \(\frac{7}{2}\)+ \(\frac{2}{2}\)) = 252
X x 6 = 252
X = 252 : 6
X= 42
Chúc bạn học tốt! ^^
\(x+x\times\frac{1}{3}\div\frac{2}{9}+x\div\frac{2}{7}=252\)
\(\Leftrightarrow x+x\times\frac{1}{3}\times\frac{9}{2}+x\times\frac{7}{2}=252\)
\(\Leftrightarrow x\left(1+\frac{1}{3}\times\frac{9}{2}+\frac{7}{2}\right)=252\)
\(\Leftrightarrow x\left(\frac{6}{6}+\frac{9}{6}+\frac{21}{6}\right)=252\)
\(\Leftrightarrow x\times\frac{36}{6}=252\)
\(\Leftrightarrow x\times6=252\)
\(\Leftrightarrow x=252\div6\)
\(\Leftrightarrow x=43\)
B=\(\frac{2002.\left(14+1\right)-1}{2001+2002.14}\)=\(\frac{2002.14+2001}{2001+2002.14}\)=1
Giải hộ mình câu này với:
(215/216+3971/3972-1/5)x(-9/35+2/5-1/7)=..........................?