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\(B=\dfrac{1}{2}x\dfrac{2}{3}x\dfrac{3}{4}x...x\dfrac{2003}{2004}\)
\(B=\dfrac{1}{2004}\)
\(B=\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times....\left(1-\dfrac{1}{2003}\right)\times\left(1-\dfrac{1}{2004}\right)\)
\(B=\dfrac{1}{2}\times\dfrac{2}{3}\times....\times\dfrac{2002}{2003}\times\dfrac{2003}{2004}\)
\(B=\dfrac{1}{2004}\)
a) \(A=\left(1-\dfrac{1}{2}\right).\left(1-\dfrac{1}{3}\right).\left(1-\dfrac{1}{4}\right).\left(1-\dfrac{1}{5}\right)...\left(1-\dfrac{1}{2003}\right).\left(1-\dfrac{1}{2004}\right)\)
\(=\dfrac{1}{2}.\dfrac{2}{3}.\dfrac{3}{4}.\dfrac{4}{5}...\dfrac{2002}{2003}.\dfrac{2003}{2004}\)
\(=\dfrac{1}{2004}\)
b) \(B=5\dfrac{9}{10}:\dfrac{3}{2}-\left(2\dfrac{1}{3}.4\dfrac{1}{2}-2.2\dfrac{1}{3}\right):\dfrac{7}{4}\)
\(=\dfrac{59}{10}:\dfrac{3}{2}-\left(\dfrac{7}{3}.\dfrac{9}{2}-2.\dfrac{7}{3}\right).\dfrac{4}{7}\)
\(=\dfrac{59}{15}-\left(\dfrac{21}{2}-\dfrac{14}{3}\right).\dfrac{4}{7}\)
\(=\dfrac{59}{15}-\dfrac{35}{6}.\dfrac{4}{7}\)
\(=\dfrac{59}{15}-\dfrac{10}{3}\)
\(=\dfrac{3}{5}\)
\(A=\left(1-\dfrac{1}{2}\right).\left(1-\dfrac{1}{3}\right).\left(1-\dfrac{1}{4}\right).\left(1-\dfrac{1}{5}\right)...\left(1-\dfrac{1}{2003}\right).\left(1-\dfrac{1}{2004}\right).\)
\(\Rightarrow A=\dfrac{1}{2}.\dfrac{2}{3}.\dfrac{3}{4}.\dfrac{4}{5}....\dfrac{2002}{2003}.\dfrac{2003}{2004}\)
\(\Rightarrow A=\dfrac{1}{2004}\)
\(B=\left(1-\dfrac{1}{2}\right)\left(1-\dfrac{1}{3}\right)...\left(1-\dfrac{1}{2004}\right)\\ =\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot\dfrac{3}{4}...\dfrac{2003}{2004}\\ =\dfrac{1}{2004}\)
\(=\frac{1}{2}\frac{2}{3}\frac{3}{4}\frac{4}{5}\frac{5}{6}\frac{6}{7}\frac{7}{8}\frac{8}{9}....\frac{2002}{2003}\frac{2003}{2004}\)
\(=\frac{1}{2004}\)
A=1/2 x 2/3 x 3/4 x ... x 2002/2003 x 2003/2004
=1/2004
XEM LẠI GIÙM MÌNH NHA!
a) x+(x+1)+(x+2)+(x+3)+...+2003=2003
x+(x+1)+(x+2)+(x+3)+...+2003=2003
X+(x+1)+(x+2)+(x+3)+...+2002=0
( Vì ta thấy đây là tổng của một dãy số các số hạng liên tiếp nên day tren co so cuoi la 2002 va tong tat ca bang 0 vi 2003-2003=0 ma)
Goi so so hang cua day so tren la n(nkhac 0)
Suy ra ta co ((2002+x).n):2=0
suy ra (2002+x).n=0
Mà n khác 0
Suy ra 2002+x=0
x=0-2002
x=-2002
Vay x=-2002
Cậu b bạn làm tương tự nhé!
Neu to co lam sai thi ban thong cam nhe!
a)\(\dfrac{1}{10000}+\dfrac{13}{10000}+\dfrac{25}{10000}+...+\dfrac{97}{10000}+\dfrac{109}{10000}\)
\(=\dfrac{1+13+25+...+97+109}{10000}\)
\(=\dfrac{\left(1+109\right)\left[109-1\right]:12+1}{20000}\)
\(=\dfrac{110.10}{20000}=\dfrac{11}{200}\)
b)\(\dfrac{4}{3}\times2019\times0,75\)
=\(\dfrac{4}{3}\times\dfrac{3}{4}\times2019\)
\(=2019\)
c)\(4\times5\times0,25\times\dfrac{1}{5}\times\dfrac{1}{2}\times2\)
\(=\left(4\times\dfrac{1}{4}\right)\left(5\times\dfrac{1}{5}\right)\left(2\times\dfrac{1}{2}\right)\)
\(=1\times1\times1=1\)
Ý d) đặt tính kiểu gì thế ?
B= 1/2 x 2/3 x 3/4 x ...........x 2002/2003 x 2003/2004
1 x 2 x 3 x 4 x .............x 2002 x 2003
2 x 3 x 4 x .............x 2003 x 2004
1
2004
\(=\frac{1}{2}x\frac{2}{3}x\frac{3}{4}x...x\frac{2002}{2003}x\frac{2003}{2004}=\frac{1x2x3x...x2002x2003}{2x3x4x...x2003x2004}=\frac{1}{2004}\)
\(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)...\left(1-\frac{1}{2003}\right).\left(1-\frac{1}{2004}\right)\)
\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}...\frac{2002}{2003}.\frac{2003}{2004}\)
\(=\frac{1.2.3...2002.2003}{2.3.4...2003.2004}=\frac{1}{2004}\)