A= -1/21 + -1/28
B= -8/18 - 15/27
C= -5/12 + 0,75
D= 3,5-{-2/7}
tính giá trị biểu thức nha giúp tui đi
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LM
7
17 tháng 8 2017
a) \(\frac{-1}{21}\)\(+\)\(\frac{-1}{28}\)\(=\)\(\frac{-1}{12}\)
b) \(\frac{-8}{18}\)\(-\)\(\frac{15}{27}\)\(=\)\(-1\)
c) \(\frac{-5}{12}\)\(+\)\(0.75\)\(=\)\(\frac{-5}{12}\)\(+\)\(\frac{3}{4}\)\(=\)\(\frac{1}{3}\)
d) \(3.5\)\(-\)\(\left(\frac{-2}{7}\right)\)\(=\)\(\frac{7}{2}\)\(+\)\(\frac{2}{7}\)\(=\)\(\frac{53}{14}\)
8 tháng 4 2017
a)\(\dfrac{-1}{21}+\dfrac{-1}{28}=\dfrac{-4-3}{84}=\dfrac{-7}{84}=\dfrac{-1}{12}\)
b)\(\dfrac{-8}{18}-\dfrac{15}{27}=\dfrac{-24-30}{54}=\dfrac{-54}{54}=-1\)
c)\(\dfrac{-5}{12}+0,75=\dfrac{-5}{12}+\dfrac{3}{4}=\dfrac{-5+9}{12}=\dfrac{4}{12}=\dfrac{1}{3}\)
d)\(3,5-\left(-\dfrac{2}{7}\right)=\dfrac{7}{2}+\dfrac{2}{7}=\dfrac{49+4}{14}=\dfrac{53}{14}\)
NT
1
DD
28 tháng 6 2023
- Tính giá trị biểu thức:
a) (2/5 x 25/29) + (3/5 x 25/29)
= (50/145) + (75/145)
= 125/145
b) (5/2 x 3/7) - (3/14 : 6/7)
= 15/14 - (3/14 x 7/6)
= 15/14 - 1/2
= (30/28) - (14/28)
= 16/28
= 4/7
c) (15/4 : 5/12) - (6/5 : 11/15)
= (15/4 x 12/5) - (6/5 x 15/11)
= 180/20 - 90/55
= 9 - 18/11
= (99/11) - (18/11)
= 81/11
= 7 4/11
- Tính giá trị biểu thức:
a) (2/3) + (20/21 x 3/2 x 7/5)
= 2/3 + (60/210)
= 2/3 + 2/7
= (14/21) + (6/21)
= 20/21
b) (5/17 x 21/32 x 47/24 x 0)
= 0
c) (11/3 x 26/7) - (26/7 x 8/3)
= (286/21) - (208/21)
= 78/21
= 3 9/21
= 3 3/7
- Tìm x:
a) (25/8) : x = 5/16
=> (25/8) x (16/5) = x
=> 4 = x
b) x + (7/15) = 6/15
=> x = (6/15) - (7/15)
=> x = -1/15
c) x : (28/49) = 7/12
=> x x (49/28) = 7/12
=> x = (7/12) x (28/49)
=> x = 1/2
- Tìm x:
a) 6 x x = (5/8) : (3/4)
=> 6x = (5/8) x (4/3)
=> 6x = 20/24
=> 6x = 5/6
=> x = (5/6) / 6
=> x = 5/36
câu,b,không,đủ,thông,tin,nhan,bạn.
28 tháng 6 2019
a) Ta có:
C = 5/18 + 8/19 - 7/21 + (-10/36 + 11/19 + 1/3) - 5/8
C = 5/18 + 8/19 - 1/3 - 5/18 + 11/19 + 1/3 - 5/8
C = (5/18 - 5/18) + (8/19 + 11/19) - (1/3 - 1/3) - 5/8
C = 1 - 5/8
c = 3/8
b) F = 15/14 - (17/23 - 80/87 + 5/4) + (17/23 - 15/14 + 1/4)
F = 15/14 - 17/23 + 80/87 - 5/4 + 17/23 - 15/14 + 1/4
F = (15/14 - 15/14) - (17/23 - 17/23) + 80/87 - (5/4 - 1/4)
F = 80/87 - 1
F = -7/87
c) G = 1/25 - 4/27 + (-23/27 + -1/25 - 5/43) + 5/43 - 4/7
G = 1/25 - 4/27 - 23/27 - 1/25 - 5/43 + 5/43 - 4/7
G = (1/25 - 1/25) - (4/27 + 23/27) - (5/43 - 5/43) - 4/7
G = -1 - 4/7 = -11/7
giúp tui đi
A = - \(\dfrac{1}{21}\) - \(\dfrac{1}{28}\)
A =- \(\dfrac{4}{84}\)- \(\dfrac{3}{84}\)
A = -\(\dfrac{7}{84}\)
A = - \(\dfrac{1}{12}\)
B = - \(\dfrac{8}{18}\) - \(\dfrac{15}{27}\)
B = - \(\dfrac{4}{9}\) - \(\dfrac{5}{9}\)
B = -1
C = - \(\dfrac{5}{12}\) + 0,75
C = -\(\dfrac{5}{12}\) + \(\dfrac{3}{4}\)
C = - \(\dfrac{5}{12}\) + \(\dfrac{9}{12}\)
C = \(\dfrac{4}{12}\)
C= \(\dfrac{1}{3}\)
D = 3,5 - { - \(\dfrac{2}{7}\))
D = \(\dfrac{7}{2}\) + \(\dfrac{2}{7}\)
D = \(\dfrac{49}{14}\) + \(\dfrac{4}{14}\)
D = \(\dfrac{53}{14}\)