bài 1: Tính nhanh
a/ -3/7 + 15 /26 - ( 2/13 - 3/7 )
b/ 2 3/7 + 2/9 - 1 3/7
c/ ( 377 /-231 - 124/89 + 34/791 ) x ( 1/6 - 1/8 - 1/24 )
bài 2: Thực hiện phép tính :
a/ 1/2 x ( 2/9 + 3/ 12 - 5/27 ) b/ ( -5/28 +1,75 + 8/35 ) : -3 9/20
c/ 1/3 x 5/7 - 3/2 x 26/14 d/ 70,5 - 528 : 15/2
b/\(1\frac{2}{9}\)
Bài 1:
a) \(-\frac{3}{7}+\frac{15}{26}-\left(\frac{2}{13}-\frac{3}{7}\right)\)
\(=-\frac{3}{7}+\frac{15}{26}-\frac{4}{26}+\frac{3}{7}\)
\(=\left(-\frac{3}{7}+\frac{3}{7}\right)+\left(\frac{15}{26}-\frac{4}{26}\right)\)
\(=0+\frac{11}{26}\)
\(=\frac{11}{26}\)
b)\(2\frac{3}{7}+\frac{2}{9}-1\frac{3}{7}\)
\(=\frac{17}{7}+\frac{2}{9}-\frac{10}{7}\)
\(=\left(\frac{17}{7}-\frac{10}{7}\right)+\frac{2}{9}\)
\(=1+\frac{2}{9}\)
\(=1\frac{2}{9}=\frac{11}{9}\)
c)\(\left(\frac{377}{-231}-\frac{124}{89}+\frac{34}{791}\right).\left(\frac{1}{6}-\frac{1}{8}-\frac{1}{24}\right)\)
\(=\left(\frac{377}{-231}-\frac{124}{89}+\frac{34}{791}\right).\left(\frac{4}{24}-\frac{3}{24}-\frac{1}{24}\right)\)
\(=\left(\frac{377}{-231}-\frac{124}{89}+\frac{34}{791}\right).0\)
\(=0\)