1A: cộng
a) 7/25+1/25
b,1/-8+-5/8
c,3/5+-7/4
d,6/13+-14/39
e,-1/21+-1/28
f,-2+-5/8
2A:
7/21+9/36
8/40+-36/45
-12/18+-21/35
-18/24+15/-21
3A:
2+7/13+6/13
1/2+1/2+1/6
1/2+-2/3+1/6+3/7
1/2+2/3+3/4+4/5+5/6
4A:
x=1/5+2/11
x=1/13+-13/26
x=1/12+3/4+-2/9
x/5=5/6+-19/30
x/7=3/7+-5/4
11/8+13/6=85/x
Loga
Sinh Học lớp 12
