\(A=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{18}-\dfrac{1}{19}+\dfrac{1}{19}-\dfrac{1}{20}\)
=1-1/20
=19/20
tìm x:
\(\frac{x}{1.2}+\frac{x}{2.3}+\frac{x}{3.4}...+\frac{x}{2017.2018}\)
Cho A=1/1.2 + 1/2.3 + + 1/ 3.4+...+1/49.50 ; B = 1.2+2.3+3.4+4.5+5.6+...+49.50
Tính 50 mủ 2 A – B/17
\(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}+\frac{1}{2^{100}}\)
Giúp mk với...
BT1; Tính;
a,2:\(\frac{-1}{3}\)+\(\frac{1}{3}\).\(\frac{2}{7}\)+\(\frac{1}{3}\).\(\frac{5}{7}\)
b,9,12+88%-1\(\frac{1}{5}\):\(\frac{1}{10}\)
c,\(\frac{5}{6}\)x+\(\frac{1}{4}\)x=\(\frac{1}{6}\)-\(\frac{5}{4}\)
Tìm x, biết:
a) \(\frac{29}{30}\)-\((\frac{13}{23}\)+x\()\)=\(\frac{7}{69}\)
b) \(\frac{1}{2}\)+\(\frac{1}{6}\)+\(\frac{1}{12}\)+...+\(\frac{1}{x\left(x+1\right)}\)=\(\frac{2011}{2012}\)
thực hiện phép cộng:
a) \(\frac{2}{5}+\frac{3}{5}\)
b) \(\frac{1}{2}+\frac{-3}{4}\)
c) \(\frac{1}{2}+\frac{1}{3}+\frac{1}{9}\)
d)\(\frac{-9}{18}+\frac{6}{12}\)
CÂU HỎI: PHÉP CỘNG PHÂN SỐ CÓ CÁC TÍNH CHẤT NÀO?
CHỨNG TỎ:
\(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{10^2}< 1\)
\(\frac{1}{3}=\frac{1}{?}+\frac{1}{?}+\frac{1}{?}\)
tìm các mẫu khác nhau
Bt1; Tính;
a,\(\frac{1}{7}\)-\(\frac{4}{7}\)
b,\(\frac{2}{3}\)+\(\frac{1}{5}\).(\(\frac{-3}{4}\))
c,\(\frac{7}{23}\)+\(\frac{4}{17}\)-\(\frac{7}{23}\)+\(\frac{13}{17}\)
d,19\(\frac{1}{4}\).\(\frac{7}{12}\)-15\(\frac{1}{4}\).\(\frac{7}{12}\)
