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17-(3x+9)=2-(-3+x) 8-3x=5-x 2x=3 X=3/2
21 tháng 6 2017

\(\left(x-3\right)\left(x^2+3x+9\right)-\left(3x-17\right)=x^3-12\)

\(\Leftrightarrow x^3-27-3x+17=x^3-12\)

\(\Leftrightarrow-10-3x=-12\)

\(\Leftrightarrow3x=2\)

\(\Leftrightarrow x=\dfrac{2}{3}\)

Vậy...

21 tháng 6 2017

\((x-3)(x^2+3x+9)-(3x-17)=x^3-12 \)

\(pt\Leftrightarrow x^3-27-3x+17=x^3-12\)

\(\Leftrightarrow x^3-3x-10-x^3+12=0\)

\(\Leftrightarrow2-3x=0\)\(\Leftrightarrow x=\dfrac{2}{3}\)

11 tháng 7 2017

\(\left(x-3\right)\left(x^2+3x+9\right)-\left(3x-17\right)=x^3-12\)

\(\Rightarrow x\left(x^2+3x+9\right)-3\left(x^2+3x+9\right)-3x+17=x^3-12\)

\(\Rightarrow x^3+3x^2+9x-3x^2-9x-27-3x+17=x^3-12\)

\(\Rightarrow x^3+\left(3x^2-3x^2\right)+\left(9x-9x\right)-3x-10=x^3+12\)

\(\Rightarrow x^3-3x-10=x^3+12\)

\(\Rightarrow x^3-3x-10-12=x^3\)

\(\Rightarrow x^3-3x-22=x^3\)

\(\Rightarrow3x-22=0\)

\(\Rightarrow3x=22\Rightarrow x=\dfrac{22}{3}\)

30 tháng 12 2020

(x-3)(x2 + 3x + 9) - (3x-17) = x(x2 - 8)

<=> x3 - 27 - 3x + 17 = x3 - 8x

<=> 5x - 10 = 0

<=> 5x = 10

<=> x = 2

Vậy ...

 

1 tháng 2 2018

(x3)(x2+3x+9)(3x17)=x312(x−3)(x2+3x+9)−(3x−17)=x3−12

x3273x+17=x312⇔x3−27−3x+17=x3−12

103x=12⇔−10−3x=−12

3x=2⇔3x=2

x=23⇔x=23

Vậy........

Nếu đúng thì k mk nha >.<

(x−3)(x2+3x+9)−(3x−17)=x^3−12

⇔x^3−27−3x+17−x^3+12=0

⇔2−3x=0

⇔3x=2⇒x=2/3

1 tháng 2 2018

(x3)(x2+3x+9)(3x17)=x312(x−3)(x2+3x+9)−(3x−17)=x3−12

x(x2+3x+9)3(x2+3x+9)3x+17=x312⇒x(x2+3x+9)−3(x2+3x+9)−3x+17=x3−12

x3+3x2+9x3x29x273x+17=x312⇒x3+3x2+9x−3x2−9x−27−3x+17=x3−12

x3+(3x23x2)+(9x9x)3x10=x3+12⇒x3+(3x2−3x2)+(9x−9x)−3x−10=x3+12

x33x10=x3+12⇒x3−3x−10=x3+12

x33x1012=x3⇒x3−3x−10−12=x3

x33x22=x3⇒x3−3x−22=x3

3x22=0⇒3x−22=0

3x=22x=223

(x−3)(x^2+3x+9)−(3x−17)=x^3−12

⇔x^3−27−3x+17=x^3−12

⇔−10−3x=−12

⇔3x=2

⇔x=2/3

Vậy...

7 tháng 9 2017

\(\left(x-3\right)\left(x^2+3x+9\right)-\left(3x-17\right)=x^3-12\)

\(\Leftrightarrow x^3-27-3x+17-x^3+12=0\)

\(\Leftrightarrow2-3x=0\)

\(\Leftrightarrow3x=2\Rightarrow x=\dfrac{2}{3}\)

\(\left(x-3\right)\left(x^2+3x+9\right)-\left(3x-17\right)=x^3-12\)

\(\Leftrightarrow x^3-27-3x+17-x^3+12=0\)

\(\Leftrightarrow-3x+2=0\)

\(\Rightarrow x=\dfrac{2}{3}\)

Vậy .............

4 tháng 8 2023

\(\left(2-x\right)^3+\left(3+x\right)\left(9-3x+x^2\right)+6x\left(1-x\right)=17\\ \Leftrightarrow8-3.2^2.x+3.2.x^2-x^3+3^3+x^3+6x-6x^2-17=0\\ \Leftrightarrow x^3-x^3+6x^2-6x^2-12x+6x=17-27-8\\ \Leftrightarrow-6x=-18\\ \Leftrightarrow x=\dfrac{-18}{-6}=3\\ Vậy:x=3\)

1 tháng 2 2018

ai nhanh nhất mk k cho nha ^^

1 tháng 2 2018

(x3)(x2+3x+9)(3x17)=x312(x−3)(x2+3x+9)−(3x−17)=x3−12

x3273x+17x3+12=0⇔x3−27−3x+17−x3+12=0

23x=0⇔2−3x=0

3x=2x=23

9 tháng 2 2021

a)  3x – 15 = 25 – 5x 

=> 3x + 5x = 25 + 15

=> 8x = 40

=> x = 5

 b) 3x - 17 = 2x – 7     

=> 3x - 2x = -7 + 17

=> x = 10

 c) 2x – 17 =  – (3x – 18)

=> 2x - 17 = -3x + 18

=> 2x + 3x = 18 + 17

=> 5x = 35

=> x = 7

d) 3x – 14 = 2(x – 9) + 1

=> 3x - 14 = 2x - 18 + 1

=> 3x - 2x = -18 + 1 + 14

=> x = -3

f) (x – 5)2 = 9          

\(\Rightarrow\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=8\\x=2\end{matrix}\right.\)

 

 

a) Ta có: \(3x-15=25-5x\)

\(\Leftrightarrow3x-15-25+5x=0\)

\(\Leftrightarrow8x-40=0\)

\(\Leftrightarrow8x=40\)

hay x=5

Vậy: x=5

b) Ta có: \(3x-17=2x-7\)

\(\Leftrightarrow3x-17-2x+7=0\)

\(\Leftrightarrow x-10=0\)

hay x=10

Vậy: x=10

c) Ta có: \(2x-17=-\left(3x-18\right)\)

\(\Leftrightarrow2x-17=-3x+18\)

\(\Leftrightarrow2x-17+3x-18=0\)

\(\Leftrightarrow5x-35=0\)

\(\Leftrightarrow5x=35\)

hay x=7

Vậy: x=7

d) Ta có: \(3x-14=2\left(x-9\right)+1\)

\(\Leftrightarrow3x-14=2x-18+1\)

\(\Leftrightarrow3x-14-2x+18-1=0\)

\(\Leftrightarrow x+3=0\)

\(\Leftrightarrow x=-3\)

Vậy: x=-3

f) Ta có: \(\left(x-5\right)^2=9\)

\(\Leftrightarrow\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=8\\x=2\end{matrix}\right.\)

Vậy: \(x\in\left\{2;8\right\}\)