1. thực hiện phép tính
a. \(\dfrac{25}{7}\)+\(\dfrac{13}{21}\)-\(\dfrac{11}{7}\)+\(\dfrac{17}{21}\)+\(\dfrac{1}{3}\)
b. (\(\dfrac{1}{3}\)+\(\dfrac{12}{67}\)+\(\dfrac{13}{41}\))-(\(\dfrac{79}{67}\)-\(\dfrac{28}{41}\))
c. (\(\dfrac{11}{4}\).\(\dfrac{-5}{9}\)-\(\dfrac{4}{9}\).\(\dfrac{11}{4}\)).\(\dfrac{8}{33}\)
d....
Đọc tiếp
1. thực hiện phép tính
a. \(\dfrac{25}{7}\)+\(\dfrac{13}{21}\)-\(\dfrac{11}{7}\)+\(\dfrac{17}{21}\)+\(\dfrac{1}{3}\)
b. (\(\dfrac{1}{3}\)+\(\dfrac{12}{67}\)+\(\dfrac{13}{41}\))-(\(\dfrac{79}{67}\)-\(\dfrac{28}{41}\))
c. (\(\dfrac{11}{4}\).\(\dfrac{-5}{9}\)-\(\dfrac{4}{9}\).\(\dfrac{11}{4}\)).\(\dfrac{8}{33}\)
d. \(\dfrac{38}{45}\)-(\(\dfrac{8}{45}\)-\(\dfrac{17}{51}\)-\(\dfrac{3}{11}\))
Ta có : a, 25/7 + 13/21 - 11/7 + 17/21 + 1/3 .
= ( 25/7 - 11/7 ) + ( 13/21 + 17/21 + 1/3 ) .
= 2 + ( 20/21 + 7/21 ) .
= 2 + 9/7 .
= 23/7 .
b, ( 1/3 + 12/67 + 13/41 ) - ( 79/67 - 28/41 ) .
= 1/3 + 12/67 + 13/41 - 79/67 + 28/41 .
= 1/3 + ( 12/67 - 79/67 ) + ( 13/41 + 28/41 ) .
= 1/3 - 1 + 1 .
= 1/3 .
c, ( 11/4 . -5/9 - 4/9 . 11/4 ) . 8/33 .
= [ 11/4 . ( -5/9 - 4/9 ) ] . 8/33 .
= [ 11/4 . ( - 1 ) ] . 8/33 .
= -11/4 . 8/33 .
= -2/3 .
d, 38/45 - ( 8/45 - 17/51 - 3/11 ) .
= 38/45 - 8/45 + 17/51 + 3/11 .
= 2/3 + 17/51 + 3/11 .
= 374/561 + 187/561 + 153/561 .
= 14/11 .