(9*7+8*9-15*9):(1+3+5+7+.....+17+19)
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a: =35/17-18/17-9/5+4/5
=1-1=0
b: =-7/19(3/17+8/11-1)
=7/19*18/187=126/3553
c: =26/15-11/15-17/3-6/13
=1-6/13-17/3
=7/13-17/3=-200/39
Phương pháp giải:
- Tính giá trị của mỗi vế
- So sánh rồi điền dấu thích hợp vào chỗ trống.
Lời giải chi tiết:
19 + 7 < 19 + 9 17 + 7 < 17 + 9
17 + 9 = 19 + 7 37 + 15 < 55 − 1
38 − 8 = 23 + 7 28 − 3 > 17 + 6
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
a) = 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
b) = 1/3 x 4/5 + 1/3 x6/5 + 1/3 x 2 = 1/3(4/5 + 6/5 + 2) = 1/3 x 4 = = 4/3
c) 4/7 x 2/9 + 4/7 x 7/9 + 2/3 = 4/7 x (2/9 + 7/9) + 2/3 = 4/7 x 1 + 2/3 = 26/21
A) 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
B) 1/3 x 4/5 + 1/3 x 6/5 + 1/3 x 2 = 1/3 x(4/5 + 6/5 x 2 ) = 1/3 x 4 = 4/3
c) TƯƠNG TỰ CÂU A VÀ B
* HOKTOT*
NHA
(9 x 7 + 8 x 9 - 15 x 9) : (1 + 3 + 5 + 7 + ... + 17 + 19)
= 9 x (7 + 8 - 15) : (1 + 3 + 5 + 7 + ... + 17 + 19)
= 9 x 0 : (1 + 3 + 5 + 7 + ... + 17 + 19)
= 0
(9 x 7 + 8 x 9 - 15 x 9) : (1 + 3 + 5 + 7 + ... + 17 + 19)
= 9 x (7 + 8 - 15) : (1 + 3 + 5 + 7 + ... + 17 + 19)
= 9 x 0 : (1 + 3 + 5 + 7 + ... + 17 + 19)
= 0