Tìm x biết: a) 2/5 - x = -7/8; b) 4/9 - 1/5 + x = -7/30
1 Tính nhanh:\\
a, A= -7/21 + ( 1 + 1/3 )
b, B= 2/15 + ( 5/9 - 6/9)
c, C= ( -1/5 -3/12)+ -3/4
d, 4/20 + 16/42 + 6/15 + -3/5 +2/21 + -10/21 + 3/20
e, 1/7 . 5/9 + -5/9 . 2/-7 + 5/-9 . 1/7 + -5/9 . 3/-7
f, 4/2.9 + 4/9.6 + 4/16.23 + .......+ 4/142.149
g, 3/5.13+ 3/13.21 + 3/21.29 +.............+ 3/166.174
2 Tìm x biết :
a, 2/5 - x = -7/8
b, 4/9-1/5 + x = -7/30
c, 2/1.3 + 2/3.5 + 2 /5.7 +.......+ 2/x(x+2) = 2018/2019
giúp E NHA MAI E HOK RỒI
a, A= -7/21 + ( 1 + 1/3 )
b, B= 2/15 + ( 5/9 - 6/9)
c, C= ( -1/5 -3/12)+ -3/4
d, 4/20 + 16/42 + 6/15 + -3/5 +2/21 + -10/21 + 3/20
e, 1/7 . 5/9 + -5/9 . 2/-7 + 5/-9 . 1/7 + -5/9 . 3/-7
f, 4/2.9 + 4/9.6 + 4/16.23 + .......+ 4/142.149
g, 3/5.13+ 3/13.21 + 3/21.29 +.............+ 3/166.174
2 Tìm x biết :
a, 2/5 - x = -7/8
b, 4/9-1/5 + x = -7/30
c, 2/1.3 + 2/3.5 + 2 /5.7 +.......+ 2/x(x+2) = 2018/2019
giúp E NHA MAI E HOK RỒI