tinh hop li: 77-11(30+7)
85(35-27)-35(85-27)
47(45-15)-47(15+45)
77-11.(30+7)
85.(35-27)-35.(85-27)
47.(45-15)-47.(45+15)
dễ mà bạn, dựa vào kiến thức dẫ học kết hợp với việc bạn làm nháp và dùng máy tính để hỗ trợ thì chắc chắc những bài trên chỉ là chuyện nhỏ
tính một cách hợp lý :
21 . 35 - 3 . 25 . 7
77 - 11 ( 30 + 7 )
85 ( 35 - 27 ) - 35 ( 85 - 27 )
47 ( 45 - 15 ) - 47 ( 45 + 15 )
21.35-3.25.7
= 21.35-21.25
= 21.(35-25)
= 21. 10
=210
77 - 11.( 30+7)
= 11.7 -11.30 -11.7
= 11.7-11.7 -11.30
= -11.30
= -330
21.35-3.25.7=210
77-11(30+7)=-330
85(35-27)-35(85-27)=-1350
47(45-15)-47(45+15)=-2820
a)21.35-3.25.7
=21.35-(3.7).25
=21.35-21.25
=21.(35-25)
=21.10=210
3.Tính hợp lí
a, 21.35-3.25.7
b, 77-11.(30+7)
c, 85.(35-27)-35.(85-27)
d, 47.(45-15)-47.(45+15)
a, 21.35-3.25.7=21.35-21.25=21.(35-25)=21.10=210
b, 77-11.(30+7)=77-330-77=-330
c, 85.(35-27)-35.(85-27)=85.35-85.27-35.85+35.27=0
d, 47.(45-15)-47.(45+15)=47.45-47.15-47.45-47.15=-2(47.15)=1410
a, 21.35-3.25.7=21.35-21.25=21.10=210
b,77-11.(30+7)=77-11.30-11.7=-11.30=-330
c,85.(35-27)-35.(85-27)=85.35-85.27-85.35+35.27=27.(-50)=-1350
d, 47.(45-15)-47.(45+15)=47.45-47.15-47.45-47.15=-47.30=-1410
a, 21 . 35 - 3 . 25 . 7
= (21 . 35) - (3 . 25 . 7)
= 735 - 525
= 210
b, 77-11.(30+7)
= 77 - 11.30 - 11.7
= -11.30
= -330
c, 85.(35-27)-35.(85-27)
= 85.35 - 85.27 - 85.35 + 35.27
= 27.(-50)
= -1350
d, 47.(45-15)-47.(45+15)
= 47.45 - 47.15 - 47.45 - 47.15
= -47.30
= -1410
Bài 2 : Tính nhanh
a)21.35-3.25.7
b)77-11.(30+7)
c)85.(35-27)-35(85-27)
d)47.(45-15)-47.(45+15)
a,21*35-3*25*7
=21*35-21*25
=21*(35-25)
=21*10
=210
b,77-11*(30+7)
=77-11*30-11*7
=11*30=330
c,
a) 21 . 35 - 3.25.7
= 21 . 35 - ( 3.7 ) . 25
= 21 . 35 - 21.25
= 21 . ( 35 - 25 )
= 21 . 10
=210
b) 77 - 11 . ( 30+7 )
= 77 -(11 . 30 + 11 . 7)
= 77 - 330 - 77
= 77 - 77 - 330
= 0 - 330
= 330
c) 85 . ( 35-27) - 35 ( 85 - 27 )
= 85 . 8 - 35 . 58
= 35 . 8 + 50 .8 - 35 . 58
= ( 35 . 8 - 35 . 58 ) + 50.8
= 35 . (-50) + 50 .8
= -35 . 50 + 50 . 8
= 50 ( -35 + 8 )
= 50 . (-27)
=-1350
d)47 . ( 45 - 15 ) - 47 . ( 45+15 )
= 47 . 30 - 47.60
= 47 ( 30 - 60 )
= 47 . (-30 )
=-1410
a,21. 35 -2.25-7
b,77-11(30+7)
c, 85(35- 27) -35(85-27)
d,47(45-15)-47(45+15)
cac ban lam nha bai de lam mik k cho
ai nhanh nhat nho noi nhe mik k cho va kb vs mik nha
a)21.243-50-7
5103-57
5046
b)77-11.37
77-407
-330
c)85.8-35.58
680-2030
-1350
d)47.30-47.60
47(30-60)
47.(-30)
-1410
tk cho mk nha
Tính
a,21. 35 - 3 . 26 . 7
b, 77 - 11 . ( 30 + 7)
c, 85. ( 36 - 27 ) - 35 . ( 86 - 27 )
d, 47 . ( 43 - 15 ) - 47 . ( 45 + 15)
a,21.35-3.26.7
=735-546
=189
b,77-11.(30+7)
=77-407
=-330
c,85.(36-27)-35.(86-27)
=85.9-35.59
=765-2065
=1300
d,47.(43-15)-47.(45+15)
=47.28-47.60
=47.(28-60)
=47.(-32)=-1504
Tính:
a) 85.(35 - 27) - 35.(85 -27)
b) 47. (45 - 15) - 47.(45+15)
a, 85.(35-27)-35.(85-27)
=85.35-85.27-35.85+35.27
=85.27+35.27
=27.(85+35)
=27.120=3240
b, 47.(45-15)-47.(45+15)
=47.30-47.60
=47.(30-60)
=-1410
tính nhanh:
a) 85.(35-27) - 35.(85-27) =
b) 47.(45-15) - 47.(45+15) =
a)85.(35-27)-35.(85-27)
=85.35-27-35.85-27
=(85-85).(35-35).(27-27)
=0.0.0
=0
b)47.(45-15)-47.(45+15)
=47.45-15-47.45+15
=(47-47).(45-45).(15+15)
=0.0.30
=0
a) 85 . ( 35 - 27 ) - 35 . ( 85 - 27 )
= 85 . 35 - 85 . 27 - 35 . 85 + 35 . 27
= ( 85 . 35 - 35 . 85 ) - 27 . ( 85 - 35 )
= 0 - 27 . 50
= 0 - 1350
= -1350
b) 47 . ( 45 - 15 ) - 47 . ( 45 + 15 )
= 47 . ( 45 - 15 - 45 - 15 )
= 47 . (-30)
= -1410
Học tốt !!!
=))
tính hợp lí
a,85.(35-27)-35.(85-27)
b,47.(45-15)-47.(45+15)
a,
85.(35-27)-35.(85-27)
=85.35-85.27-35.85-35.27
=85.35-35.85-85.27.35.27
=85.27-35.27
=(85-35).27
=100.27/2
=2700/2
=1350