Bài 12: Tính hợp lí ( nếu có thể)
a) 5/7 – 10/21 + 2/7
b) 5/7- 1/2+ 2/7+ (-3)/2
c) (-9)/15+ 1/6- (-5)/6
d) (-4)/26- 1/5- (-3)/10
e) 1/9+ (-3)/5+1/(-9)- 2/5
f) ( 23/7- 8/11 ) – ( 25/11 – 5/7 )
Bài 12: Tính hợp lí ( nếu có thể) a) 5/7 – 10/21 + 2/7 b) 5/7- 1/2+ 2/7+ (-3)/2 c) (-9)/15+ 1/6- (-5)/6 d) (-4)/26- 1/5- (-3)/10 e) 1/9+ (
By Samantha
a) 5/7 – 10/21 + 2/7
=(5/7+2/7)-10/21
= 1-10/21
= 11/21
b) 5/7- 1/2+ 2/7+ (-3)/2
=(5/7+2/7)+(-1/2-3/2)
= 1-2
= -1
c) (-9)/15+ 1/6- (-5)/6
= -9/15 + 1/6+5/6
= -9/15+1
= 2/5
d) (-4)/26- 1/5- (-3)/10
= -4/26-1/5+3/10
= -4/26+(-1/5+3/10)
= -4/26+1/10
= -7/130
e) 1/9+(-3)/5+1/(-9)-2/5
=(1/9+1/-9)+(-3/5-2/5)
= 0-1
= -1
f) ( 23/7- 8/11 ) – ( 25/11 – 5/7 )
=23/7- 8/11- 25/11 + 5/7
= ( 23/7+ 5/7)+(- 8/11- 25/11)
= 4-3
= 1
cho mk hay nhất nhé
Bạn tham khảo