Bài 1:tính hợp lí
1, 8 – ( 2014 – 2008) + 2014 2,5679 + (1357 – 5679) – 17
3, 1268 – ( 78+1268) – (-78) 4,13567 – (15 – 27) + (-13567)
5, -48795 – (489 – 48795)+400 6, 15641 – (27 + 15641) + (72)
Đáp án+Giải thích các bước giải:
`1, 8 – ( 2014 – 2008) + 2014`
`=8-2014+2014+2008`
`=2008+8`
`=2016`
`2,5679 + (1357 – 5679) – 17`
`=5679-5679+1357-17`
`=1357-17`
`=1340`
`3, 1268 – ( 78+1268) – (-78)`
`=1268-1268-78+78`
`=0`
`4,13567 – (15 – 27) + (-13567)`
`=13567-13567-15+27`
`=27-15`
`=12`
`5, -48795 – (489 – 48795)+400`
`=48795-48795+400-489`
`=400-489`
`=-89`
`6, 15641 – (27 + 15641) + (72)`
`=15641-15641-27+72`
`=72-27`
`=45`
Đáp án:
1) 8 – (2014 – 2008) + 2014
= 8 – 2014 + 2008 + 2014
= (8 + 2008) + (-2014 + 2014)
= 2016 + 0
= 0
2) 5679 + (1357 – 5679) – 17
= 5679 + 1357 – 5679 – 17
= (5679 – 5679) + (1357 – 17)
= 0 + 1340
= 1340
3) 1268 – (78 + 1268) – (-78)
= 1268 – 78 – 1268 + 78
= (1268 – 1268) + (-78 + 78)
= 0 + 0
= 0
4) 13567 – (15 – 27) + (-13567)
= 13567 – (-12) + (-13567)
= 13567 + 12 + (-13567)
= (-13567 + 13567) + 12
= 0 + 12
= 12
5) -48795 – (489 – 48975) + 400
= -48795 – 489 + 48975 + 400
= (-48795 + 48795) + (-489 + 400)
= 0 + (-89)
= -89
6) 15641 – (27 + 15641) + (72)
= 15641 – 27 – 15641 + 72
= (15641 – 15641) + (-27 + 72)
= 0 + 45
= 45
Chúc học tốt!!!