bài 1
a)-1/4+3/4+-5/4
b)1,4.15/49-(4/5+2/3):11/5
bài 2 : tính hợp lí
a)-7/15+3/11-2/7–7/15+-14/11
b)113.(-11)+113.(-115)-13.(-126)
giúp mình với !!
bài 1 a)-1/4+3/4+-5/4 b)1,4.15/49-(4/5+2/3):11/5 bài 2 : tính hợp lí a)-7/15+3/11-2/7–7/15+-14/11 b)113.(-11)+113.(-115)-13.(-126) giúp mình với !!
By Reagan
Bài 1
a)-1/4+3/4+(-5/4)
= -1 +3+(-5)
4
=-3/4
b)1,4.15/49-(4/5+2/3):11/5
=7/5.15/49-(12/15+10/15).5/11
=3/7-22/15.5/11
=3/7-2/3
=9/21-14/21
=-5/21
Bài2
a)-7/15+3/11-2/7-(-7/15)+(-14/11)
=-7/15+3/11-2/7+7/15-14/11
=(-7/15+7/15)+(3/11-14/11)-2/7
=0+(-1)-2/7
=-1-2/7
=-7/7-2/7
=-9/7
b)113.(-11)+113.(-115)-13.(-126)
=113.[-11+(-115)]-13.(-126)
=113.(-126)-13.(-126)
=113.(-126)-13.-126
=-126.(113-13)
=-126.100
=-12600
Đáp án:
Bài 1
$a,$ `-1/4 + 3/4 + (-5/4)`
`= 2/4 + (-5/4)`
`= -3/4`
$b,$ `1,4 . 15/49 – (4/5 + 2/3) : 11/5`
`= 3/7 – 22/15 : 11/5`
`= 3/7 – 2/3`
`= (-5)/21`
Bài 2
$a,$ `-7/15 + 3/11 – 2/7 – (-7/15) + (-14/11)`
`= -7/15 + 3/11 – 2/3 + 7/15 – 14/11`
`= (-7/15 + 7/15) + (3/11 – 14/11) – 2/3`
`= 0 – 1 – 2/3`
`= -1 – 2/3`
`= -5/3`
$b,$ `113 . (-11) + 113 . (-115) – 13 . (-126)`
`= 113 . [-11 + (-115)] – 13 . (-126)`
`= 113 . (-126) – 13 . (-126)`
`= -126 . (113 – 13)`
`= -126 . 100`
`= -12600`