3/1x4+3/4x7+...+3/97x100
=1-1/4+1/4-1/7+1/7-...+1/97-1/100
=1-1/100
=99/100
\(\frac{3}{1.4}+\frac{3}{4.7}+...+\frac{3}{97.100}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{100}\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)
\(\frac{3}{1x4}+\frac{3}{4x7}+\frac{3}{7x10}+\frac{3}{10x13}+.....+\frac{3}{97x100}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+.......+\frac{1}{97}-\frac{1}{100}\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)
\(\frac{3}{1\times4}+\frac{3}{4\times7}+\frac{3}{7\times10}+\frac{3}{10\times13}+...+\frac{3}{97\times100}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+...+\frac{1}{97}-\frac{1}{100}\)
\(=1+\left(\frac{1}{4}-\frac{1}{4}\right)+\left(\frac{1}{7}-\frac{1}{7}\right)+...+\left(\frac{1}{97}-\frac{1}{97}\right)-\frac{1}{100}\)
\(=1-\frac{1}{100}=\frac{99}{100}\)
~ Hok tốt ~
\(\frac{3}{1x4}+\frac{3}{4x7}+\frac{3}{7x10}+\frac{3}{10x13}+...+\frac{3}{97x100}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+...+\frac{1}{97}-\frac{1}{100}\)
\(=1-\frac{1}{100}=\frac{99}{100}.\)
=)) A=1-1/4+1/4-1/7+...+1/97-1/100
=))A=1-1/100
=))A=99/100
Các bạn nhớ k đúng cho mình rồi minh rồi minh k lại cho
\(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{10}-\frac{1}{13}+..........+\frac{1}{97}-\frac{1}{100}\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)
Bài làm :
Ta có :
\(\frac{3}{1\times4}+\frac{3}{4\times7}+\frac{3}{7\times10}+\frac{3}{10\times13}+...+\frac{3}{97\times100}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+...+\frac{1}{97}-\frac{1}{100}\)
\(=1+\left(\frac{1}{4}-\frac{1}{4}\right)+\left(\frac{1}{7}-\frac{1}{7}\right)+...+\left(\frac{1}{97}-\frac{1}{97}\right)-\frac{1}{100}\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)
