\(\frac{1}{1\times3}+\frac{2}{3\times5}+..........+\frac{2}{99\times101}\)
\(=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+........+\frac{1}{99}-\frac{1}{101}\)
\(=1-\frac{1}{101}\)
\(=\frac{100}{101}\)
\(\frac{2}{3x5}+\frac{2}{5x7}+\frac{2}{7x9}+....+\frac{2}{99x101}\)
\(B=\frac{2}{1x3}+\frac{2}{3x5}+\frac{2}{5x7}+.....+\frac{2}{57x59}\)
2\1x3+2\3x5+2\5x7+...+2\99x101
A=2/1x3+2/3x5+2/5x7+....+2/99x101
Tính bằng cách thuận tiện.
S=\(\frac{2}{1X3}\)+\(\frac{2}{3X5}\)+\(\frac{2}{5X7}\)+.....+\(\frac{2}{2015X2017}\)
help me !!!
bài 15
a) 2/1x3 + 2/3x5 + 2/5.7+......+2/99x101
b) 5/1x3 + 5/3x5 + 5/5x7+......+5/99x101
bài 16
chứng tỏ rằng phân số 2n+1/3n+1 là phân số tối giản
bạn nào làm đc đầu tiên mk tick nha
tính:
a) \(\frac{1^2}{1x2}+\frac{2^2}{2x3}+\frac{3^2}{3x4}+...+\frac{100^2}{100x101}\)
b) \(\frac{2^2}{1x3}+\frac{3^2}{2x4}+\frac{4^2}{3x5}+...+\frac{59^2}{58x60}\)
\(\frac{2^2}{1x3}\)x\(\frac{4^{^2}}{3x5}\)x\(\frac{6^2}{5x7}\)x\(\frac{8^2}{7x9}\)
Tính tổng:
A= \(\frac{1}{15}\)+\(\frac{1}{35}\)+...+\(\frac{1}{2499}\)
B=\(\frac{5}{1x4}\)+\(\frac{5}{4x7}\)+...+\(\frac{5}{100x103}\)
C=\(\frac{5}{1x3}\)+\(\frac{5}{3x5}\)+\(\frac{5}{5x7}\)+...+\(\frac{5}{99x101}\)
