Lời giải:

\(H=2-\frac{3}{17}-\frac{5}{23}+\frac{2}{17}-\frac{1}{2023}-\frac{16}{17}-\frac{18}{23}\\ =2-(\frac{3}{17}-\frac{2}{17}+\frac{16}{17})-(\frac{5}{23}+\frac{18}{23})-\frac{1}{2023}\\ =2-1-1-\frac{1}{2023}=-\frac{1}{2023}\)

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\(K=\frac{7}{23}.\frac{-11}{17}+\frac{7}{23}.\frac{4}{17}-\frac{7}{23}.\frac{10}{17}\\ =\frac{7}{23}(\frac{-11}{17}+\frac{4}{17}-\frac{10}{17})\\ =\frac{7}{23}.\frac{-17}{17}=\frac{-7}{23}\)

trl giúp em đy :)

7⁴ = 2401

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343.49² = 7³.(7²)² = 7⁷ = 823543

5^2x-2 + 2².5² = 5³

5^2x-2 + 100 = 125

5^2x-2          = 125 - 100

5^2x-2          = 25

5^2x-2          =   5²

        2x- 2  = 2

            2x   = 2 + 2

             2x = 4

               x = 4:2

               x = 2

52x-2 + 22.52 = 53

52x-2 + 100 = 125

52x-2          = 125 - 100

52x-2          = 25

52x-2          =   52

        2x- 2  = 2

            2x   = 2 + 2

             2x = 4

               x = 4:2

               x = 2

(-1) + 2 +( -3 ) +4 + ( -4 ) +...+98 + (-99)

Sửa đề chút...

(-1) + 2 +( -3 ) +4 + ( -5 ) +...+98 + (-99)

[(-1) + 2] + [( -3 ) +4] + [( -5 ) + 6] +...+ [98 + (-99)]  (48 cặp)

 1          +     1         +     1      +...+    1 ( 48 số 1)

=48

#ht

Câu 2: 

1: \(\Leftrightarrow x\cdot\dfrac{7}{2}=\dfrac{9}{2}+3=\dfrac{15}{2}\)

hay x=15/7

2: \(\Leftrightarrow x=\dfrac{5}{2}\cdot\dfrac{8}{5}=4\)

3: \(\Leftrightarrow x=\dfrac{-11\cdot10}{5}=-11\cdot2=-22\)

4: =>2x=90

hay x=45

\(\dfrac{5}{11}\cdot\dfrac{3}{17}+\dfrac{5}{11}\cdot\dfrac{8}{17}=\dfrac{5}{11}\cdot\left(\dfrac{3}{17}+\dfrac{8}{17}\right)=\dfrac{5}{11}\cdot\dfrac{11}{17}=\dfrac{5}{17}\)

5/11 . 3/17 + 5/11 . 8/17

\(=\dfrac{5}{11}.\left(\dfrac{8}{17}+\dfrac{3}{17}\right)=\dfrac{5}{11}.\dfrac{11}{17}=\dfrac{5}{17}\)

• vydtk10dpascal
• 

Đáp án:

Ta có: xy - 2x + y = 3

          x(y-2)+(y-2)=3-2

          (x+1)(y-2)=1=1.1=-1.-1

ta có bảng sau

x+1|  1 |-1

y-2 | 1  | -1 

 x   |   0  |  2

 y |     3 |   1

 Vậy x thuộc{..............}