Ta có: \(\frac{6}{7}\cdot\frac{8}{13}+\frac{9}{13}\cdot\frac{6}{7}-\frac{3}{13}\cdot\frac{6}{7}\)
\(=\frac{6}{7}\cdot\left(\frac{8}{13}+\frac{9}{13}-\frac{3}{13}\right)\)
\(=\frac{6}{7}\cdot\frac{14}{13}=2\cdot\frac{6}{13}=\frac{12}{13}\)
4/5 : ( 4/5 . -5/4) : ( 16/25 - 1/5 )
11/12 : ( 7/9 + -1/3 ) - ( 2/3 - 5/15 )
-2/5 . ( 9/8 + 16/32 -3/4 ) - 9/10
( 4/3 + 8/3 ) . ( 7/4 - 6/4 ) : ( 6/5 + 12/5 + 1/5 )
4/5 : ( 4/5 . -5/4) : ( 16/25 - 1/5 )
11/12 : ( 7/9 + -1/3 ) - ( 2/3 - 5/15 )
-2/5 . ( 9/8 + 16/32 -3/4 ) - 9/10
( 4/3 + 8/3 ) . ( 7/4 - 6/4 ) : ( 6/5 + 12/5 + 1/5 )
Tính :
a) \(\dfrac{-5}{6}:\dfrac{3}{13}\)
b) \(-\dfrac{4}{7}:-\dfrac{1}{11}\)
c) \(-15:\dfrac{3}{2}\)
d) \(\dfrac{9}{3}:-\dfrac{3}{5}\)
e) \(\dfrac{5}{9}:\dfrac{5}{-3}\)
g) \(0:-\dfrac{7}{11}\)
h) \(\dfrac{3}{4}:\left(-9\right)\)
Tính theo cách hợp lí:
e) -52 . 4 : (-2) - 18 : (-3) + 3
f) -|-16 - 12| : 7 - 7 . (-3)2 - (-6)2
g) (-49 + 13) : (-2)2 - 43 : (-2)3
h) [3 . (-5)5 - 13 . (-5)5 ] : (-5)4
Tìm \(x\) biết :
a) \(x.\dfrac{3}{7}=\dfrac{2}{3}\)
b) \(x:\dfrac{8}{11}=\dfrac{11}{3}\)
c) \(\dfrac{2}{5}:x=-\dfrac{1}{4}\)
d) \(\dfrac{4}{7}.x-\dfrac{2}{3}=\dfrac{1}{5}\)
e) \(\dfrac{2}{9}-\dfrac{7}{8}.x=\dfrac{1}{3}\)
g) \(\dfrac{4}{5}+\dfrac{5}{7}:x=\dfrac{1}{6}\)
tìm x,biết :
a)\(\frac{12}{7}:x=\frac{-22}{21}\)
b)\(x:\frac{3}{4}=\frac{-5}{6}+\frac{7}{8}\)
c)\(x:\frac{3}{4}+\frac{5}{6}=\frac{7}{8}\)
d)\(\frac{2}{3}:x-\frac{3}{4}=\frac{5}{4}\)
Tính :
a) \(\dfrac{4}{7}:\left(\dfrac{2}{5}.\dfrac{4}{7}\right)\)
b) \(\dfrac{6}{7}+\dfrac{5}{7}:5-\dfrac{8}{9}\)
Tìm hai số, biết rằng \(\dfrac{9}{11}\) của số này bằng \(\dfrac{6}{7}\) của số kia và tổng của hai số đó bằng 28 ?
M=\(\dfrac{\dfrac{7}{2012}+\dfrac{7}{9}-\dfrac{1}{4}}{\dfrac{5}{9}-\dfrac{3}{2012}-\dfrac{1}{2}}\) tính M
