Giải : 

\(A=\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)

Ta có : 
A= 6 - 5 - 3 - \(\frac{2}{3}\) - \(\frac{5}{3}\) + \(\frac{7}{3}\) + \(\frac{1}{2}\) + \(\frac{3}{2}\) - \(\frac{5}{2}\) 
= - 2 - \(\frac{1}{2}\) = \(-\frac{5}{2}\)

a: \(=5\cdot5\sqrt{3}-\dfrac{1}{3}\cdot3\sqrt{3}=24\sqrt{3}\)

b: \(=\dfrac{12\left(3+\sqrt{5}\right)}{4}=9+3\sqrt{5}\)

c: \(=3-\sqrt{5}+\sqrt{5}=3\)

2:

a: \(=\dfrac{1}{3}\left(-\dfrac{4}{5}-\dfrac{6}{5}\right)=-\dfrac{1}{3}\cdot2=-\dfrac{2}{3}\)

1:

\(A=7-\dfrac{3}{4}+\dfrac{1}{3}-6-\dfrac{5}{4}+\dfrac{4}{3}-5+\dfrac{7}{4}-\dfrac{5}{3}\)

\(=-4-\dfrac{1}{4}=-\dfrac{17}{4}\)

Bài 1:

\(A=\left(7-\dfrac{3}{4}+\dfrac{1}{3}\right)-\left(6+\dfrac{5}{4}-\dfrac{4}{3}\right)-\left(5-\dfrac{7}{4}+\dfrac{5}{3}\right)\)

\(A=7-\dfrac{3}{4}+\dfrac{1}{3}-6-\dfrac{5}{4}+\dfrac{4}{3}-5+\dfrac{7}{4}-\dfrac{5}{3}\)

\(A=\left(7-6-5\right)-\left(\dfrac{3}{4}+\dfrac{5}{4}-\dfrac{7}{4}\right)+\left(\dfrac{1}{3}+\dfrac{4}{3}-\dfrac{5}{3}\right)\)

\(A=-4-\dfrac{3+5-7}{4}+\dfrac{1+4-5}{3}\)

\(A=-4-\dfrac{1}{4}+\dfrac{0}{3}\)

\(A=-\dfrac{16}{4}-\dfrac{1}{4}+0\)

\(A=\dfrac{-16-1}{4}\)

\(A=-\dfrac{17}{4}\)

Bài 2:

\(\dfrac{1}{3}\cdot-\dfrac{4}{5}+\dfrac{1}{3}\cdot-\dfrac{6}{5}\)

\(=\dfrac{1}{3}\cdot\left(-\dfrac{4}{5}-\dfrac{6}{5}\right)\)

\(=\dfrac{1}{3}\cdot\dfrac{-4-6}{5}\)

\(=\dfrac{1}{3}\cdot\dfrac{-10}{5}\)

\(=\dfrac{1}{3}\cdot-2\)

\(=-\dfrac{2}{3}\)

A = 1

a) Khi tính giá trị của biểu thức có chứa dấu ( ) thì ta thực hiện các phép tính trong ngoặc trước.

b) Tính :

3 x (17 + 22) = 3 x 39 = 117

Giá trị của biểu thức 3 x (17 + 22) là 117.

(58 – 23) : 5 = 35 : 5 = 7.

Giá trị của biểu thức (58 – 23) : 5 = 7.

Với a = 8 thì giá trị của biểu thức 127 + 8 x 6 = 127 + 48 = 175

= 60x² + 35x - ( 60x² - 15x + 20x - 5 ) = 60x² + 35x - 60x² +15x - 20x +5 = 30x + 5 => đề sai

Cách 1:

A=(3+ 1/2 -2/3 ) -( 2- 2/3 +5/2) - (5- 5/2 + 4/3)

A=17/6-23/6-23/6

A=-29/6

Cách 2:

A=(3+ 1/2 -2/3 ) -( 2- 2/3 +5/2) - (5- 5/2 + 4/3)

A=3+ 1/2 -2/3 - 2+ 2/3 -5/2 - 5+ 5/2 - 4/3

A=-29/6

cách 1:

\(A=\left(3+\frac{1}{2}-\frac{2}{3}\right)-\left(2-\frac{2}{3}+\frac{5}{2}\right)-\left(5-\frac{5}{2}+\frac{4}{3}\right)\)

\(=3+\frac{1}{2}-\frac{2}{3}-2+\frac{2}{3}-\frac{5}{2}-5+\frac{5}{2}-\frac{4}{3}=-4+\frac{1}{2}-\frac{4}{3}\)

\(=\frac{-24}{6}+\frac{3}{6}-\frac{8}{6}=-\frac{29}{6}\)

cách 2:

\(A=\left(3+\frac{1}{2}-\frac{2}{3}\right)-\left(2-\frac{2}{3}+\frac{5}{2}\right)-\left(5-\frac{5}{2}+\frac{4}{3}\right)\)

\(=\left(\frac{18}{6}+\frac{3}{6}-\frac{4}{6}\right)-\left(\frac{12}{6}-\frac{4}{6}+\frac{15}{6}\right)-\left(\frac{30}{6}-\frac{15}{6}+\frac{8}{6}\right)\)

\(=\frac{17}{6}-\frac{23}{6}-\frac{23}{6}=-\frac{29}{6}\)

Câu 1:

\(A=\frac{2^5.7+2^5}{2^5.3-2^5}\)= \(\frac{2^5.8}{2^5.2}\)= 4

Vậy A = 4

Câu 2:

\(B=2^3.5^3-3.\left\{400-\left[673-2^3.\left(7^8:7^6+7^0\right)\right]\right\}\)

\(B=8.125-3.\left\{400-\left[673-8.\left(7^2+1\right)\right]\right\}\)

\(B=1000-3.\left\{400-\left[673-8.\left(49+1\right)\right]\right\}\)

\(B=1000-3.\left\{400-\left[673-8.50\right]\right\}\)

\(B=1000-3.\left\{400-\left[673-400\right]\right\}\)

\(B=1000-3.\left\{400-273\right\}\)

\(B=1000-3.127\)

\(B=1000-381\)

\(B=619\)

Vậy B = 619

1. 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

1. 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

1. 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

1. 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.