\(A=\frac{12}{1.5}+\frac{12}{5.9}+\frac{12}{9.13}+.............+\frac{12}{101.105}\)
\(=3.\left(\frac{4}{1.5}+\frac{4}{5.9}+\frac{4}{9.13}+............+\frac{4}{101.105}\right)\)
\(=3\left(1-\frac{1}{105}\right)\)
\(=3.\frac{104}{105}=\frac{312}{105}\)
a,\(\frac{2}{3}x-\frac{3}{2}\left(x-\frac{1}{2}\right)=\frac{5}{12}\)
b,\(\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+........+\frac{2}{x\left(x+1\right)}=\frac{2}{9}\)
\(\frac{1}{1.5}+\frac{1}{5.9}+\frac{1}{9.13}+...+\frac{1}{x.\left(x+4\right)}\)
tìm A khi x bằng 12, 2, \(\frac{5}{6}\)
Câu 1 Tính:
a. M= \(\frac{363636.37-373737.36}{1+2+3+...+2013}\)
b, B= (\(\frac{1}{11}+\frac{1}{21}+\frac{1}{31}+\frac{1}{41}+\frac{1}{51}\)) x (\(\frac{123}{738}-\frac{1342}{2013}-\frac{-1007}{2014}\))
c, D= \(\frac{12}{6.7}+\frac{12}{7.22}+\frac{12}{22.15}+\frac{12}{15.38}+...+\frac{12}{97.202}\)
Tìm x biết :
a) \(\frac{1}{2013}\times x+1+\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{2012\times2013}=2\)
b)\(2x+\frac{7}{6}+\frac{13}{12}+\frac{21}{20}+\frac{31}{30}+\frac{43}{42}+\frac{57}{56}+\frac{73}{72}+\frac{91}{90}=10\)
\(2+\frac{2}{3}+\frac{2}{12}+.....+\frac{2}{X\left(X-1\right)}=1\frac{1989}{1991}\)
1989 PHẦN 1991 NHA MK VT THIẾU
\(\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+.....+\frac{2}{X\left(X+1\right)}=\frac{2}{9}\) \(X-\frac{20}{11.13}-\frac{20}{13.15}-\frac{20}{15.17}-.....-\frac{20}{53.55}=\frac{3}{11}\)
GIÚP MÌNH NHA MẤY BẠN 10H CHỐT NHA . AI TRẢ LỜI ĐÚNG VÀ NHANH MK TIK CHO
Tìm số tự nhiên x, biết:
a, \(x-\frac{20}{11.13}-\frac{20}{13.15}-\frac{20}{15.17}-....-\frac{20}{53-55}=\frac{3}{11}\)
b, \(x+\frac{4}{5.9}+\frac{4}{9.13}+\frac{4}{13.17}+...+\frac{4}{41.45}=\frac{-37}{45}\)
c,\(\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+\frac{2}{x\left(x+1\right)}=\frac{2}{9}\)
Tìm x biết:
a)\(\frac{x+1}{10}+\frac{x+1}{11}+\frac{x+1}{12}=\frac{x+1}{13}+\frac{x+1}{14}\)
b)\(\frac{x+1}{14}+\frac{x+2}{13}=\frac{x+3}{12}+\frac{x+4}{11}\)
Tính nhanh
a, \(\frac{7}{13}\)x\(\frac{7}{15}\)-\(\frac{5}{12}\)x\(\frac{21}{39}\)+\(\frac{49}{91}\)x\(\frac{8}{15}\)3
b,(\(\frac{12}{199}\)+\(\frac{23}{200}\)-\(\frac{34}{201}\)) x (\(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\))
Tim x biet
a)\(\frac{8}{23}.\frac{46}{24}-x=\frac{1}{3}\)
b) \(\frac{10}{12}:x=\frac{28}{9}.\frac{3}{56}\)
c) \(\frac{x-12}{4}=\frac{1}{2}\)
