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9 tháng 9 2017

1 tháng 9 2021

\(\left[\left(3-x\right)^5-7\left(x-3\right)^4-4\left(x-3\right)^2\right]:\left(x^2-6x+9\right)=\left[\left(3-x\right)^5-7\left(3-x\right)^4-4\left(3-x\right)^2\right]:\left(3-x\right)^2=\left(3-x\right)^2\left[\left(3-x\right)^3-7\left(3-x\right)^2-4\right]:\left(3-x\right)^2=\left(3-x\right)^3-7\left(3-x\right)^2-4=27-27x+9x^2-x^3-63+42x-7x^2-4=-x^3+2x^2+15x-40\)

\(\dfrac{\left(3-x\right)^5-7\left(x-3\right)^4-4\left(x-3\right)^2}{x^2-6x+9}\)

\(=\dfrac{-\left(x-3\right)^5-7\left(x-3\right)^4-4\left(x-3\right)^2}{\left(x-3\right)^2}\)

\(=-\left(x-3\right)^3-7\left(x-3\right)^2-4\)

28 tháng 10 2017

Có:

\(\left[7\left(x-y\right)^5+6\left(y-x\right)^4-2\left(x-y\right)^3+\left(y-x\right)^2\right]:\left(x-y\right)^2\)

\(=\left[7\left(x-y\right)^5+6\left(x-y\right)^4-2\left(x-y\right)^3+\left(x-y\right)^2\right]:\left(x-y\right)^2\)

\(=\left[7\left(x-y\right)^5:\left(x-y\right)^2\right]+\left[6\left(x-y\right)^4:\left(x-y\right)^2\right]-\left[2\left(x-y\right)^3:\left(x-y\right)^2\right]+\left(x-y\right)^2:\left(x-y\right)^2\)

\(=7\left(x-y\right)^3+6\left(x-y\right)^2-2\left(x-y\right)+1\)

Bài 3:

3: \(6x\left(x-y\right)-9y^2+9xy\)

\(=6x\left(x-y\right)+9xy-9y^2\)

\(=6x\left(x-y\right)+9y\left(x-y\right)\)

\(=\left(x-y\right)\left(6x+9y\right)\)

\(=3\left(2x+3y\right)\left(x-y\right)\)

Bài 4:

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a) Ta có: \(\dfrac{x}{x-3}-\dfrac{6}{x}-\dfrac{9}{x^2-3x}\)

\(=\dfrac{x^2}{x\left(x-3\right)}-\dfrac{6\left(x-3\right)}{x\left(x-3\right)}-\dfrac{9}{x\left(x-3\right)}\)

\(=\dfrac{x^2-6x+18-9}{x\left(x-3\right)}\)

\(=\dfrac{\left(x-3\right)^2}{x\left(x-3\right)}=\dfrac{x-3}{x}\)

b) Ta có: \(\dfrac{7}{x}-\dfrac{x}{x+6}+\dfrac{36}{x^2+6x}\)

\(=\dfrac{7\left(x+6\right)-x^2+36}{x\left(x+6\right)}\)

\(=\dfrac{7x+42-x^2+36}{x\left(x+6\right)}\)

\(=\dfrac{-\left(x^2-7x-78\right)}{x\left(x+6\right)}\)

\(=\dfrac{-\left(x^2-13x+6x-78\right)}{x\left(x+6\right)}\)

\(=\dfrac{-\left[x\left(x-13\right)+6\left(x-13\right)\right]}{x\left(x+6\right)}\)

\(=\dfrac{13-x}{x}\)

c) Ta có: \(\dfrac{6}{x-3}-\dfrac{2x-6}{x^2-9}-\dfrac{4}{x+3}\)

\(=\dfrac{6\left(x+3\right)-2x+6-4\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}\)

\(=\dfrac{6x+18-2x+6-4x+12}{\left(x-3\right)\left(x+3\right)}=\dfrac{36}{\left(x-3\right)\left(x+3\right)}\)

4 tháng 9 2018

\(2x^7+x^5+2\div x^2+x+1=2x^5-3x^3-3x^2+1\left(dư1-x\right)\)

HQ
Hà Quang Minh
Giáo viên
19 tháng 9 2023

\(\begin{array}{l}a)3{x^7}:\dfrac{1}{2}{x^4} = (3:\dfrac{1}{2}).({x^7}:{x^4}) = 6{x^3}\\b)( - 2x):x = [( - 2):1].(x:x) =  - 2\\c)0,25{x^5}:( - 5{x^2}) = [0,25:( - 5)].({x^5}:{x^2}) =  - 0,05.{x^3}\end{array}\)

25 tháng 10 2018

B1

B = 52 . 4 - ( 18 + 6 . 7 ) : 81 : 33

= 25 . 4 - ( 18 + 42 ) : 34 : 33

= 100 - 60 : 3

= 100 - 20

= 80

B2

5x+1 + 52 = 62 + ( 79 : 77 - 23 )

=> 5x+1 + 52 = 36 + ( 72 - 8 )

=> 5x+1 + 52 = 36 + 41

=> 5x+1 + 52 = 77

=> 5x+1 = 25

=> 5x+1 = 52

=> x + 1 = 2

=> x = 1

\(+)18⋮x-3\)

\(\Rightarrow x-3\inƯ\left(18\right)\)

mà \(Ư\left(18\right)=\left\{1;2;3;6;9;18\right\}\)

\(\Rightarrow\hept{\begin{cases}x-3=1;x-3=6\\x-3=2;x-3=9\\x-3=3;x-3=18\end{cases}}\)

\(\Rightarrow\hept{\begin{cases}x=4;x=9\\x=5;x=12\\x=6;x=21\end{cases}}\)

\(26⋮\left(x+1\right)\)

\(\Rightarrow\left(x+1\right)\inƯ\left(26\right)\)

mà \(Ư\left(26\right)=\left\{1;2;13;26\right\}\)

\(\Rightarrow\orbr{\begin{cases}x+1=1\\x+1=2\end{cases}}\orbr{\begin{cases}x+1=13\\x+1=26\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x=1\end{cases}}\orbr{\begin{cases}x=12\\x=25\end{cases}}\)

24 tháng 5 2019

a)  x 2  + 2x + 1.            b) x + 3.         c)  x 2  – x + 1.

HQ
Hà Quang Minh
Giáo viên
20 tháng 9 2023

\((6{x^2} + 4x):2x = (6{x^2}:2x) + (4x:2x)\)

\( = 3x + 2\)