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8x³=50x

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8x³ - 50x = 0

⇔ 2x( 4x² - 25 ) = 0

⇔ 2x( 2x - 5 )( 2x + 5 ) = 0

⇔ 2x = 0 hoặc 2x - 5 = 0 hoặc 2x + 5 = 0

⇔ x = 0 hoặc x = ±5/2

( x + 3 )² = 9( 2x - 1 )²

⇔ ( x + 3 )² - 3²( 2x - 1 )² = 0

⇔ ( x + 3 )² - [ 3( 2x - 1 ) ]² = 0

⇔ ( x + 3 )² - ( 6x - 3 )² = 0

⇔ ( x + 3 - 6x + 3 )( x + 3 + 6x - 3 ) = 0

⇔ ( -5x + 6 ).7x = 0

⇔ -5x + 6 = 0 hoặc 7x = 0

⇔ x = 6/5 hoặc x = 0

\(8x^3-50x=0\)   

\(2x\left(4x^2-25\right)=0\)   

\(\orbr{\begin{cases}2x=0\\4x^2-25=0\end{cases}}\)   

\(\orbr{\begin{cases}x=0\\x^2=\frac{25}{4}\end{cases}}\)   

\(\orbr{\begin{cases}x=0\\x=\pm\sqrt{\frac{25}{4}}\end{cases}}\)   

\(\orbr{\begin{cases}x=0\\x=\pm\frac{5}{2}\end{cases}}\)   

\(\left(x+3\right)^2=9\left(2x-1\right)^2\)   

\(x^2+6x+9=9\left(4x^2-4x+1\right)\)   

\(x^2+6x+9=36x^2-36x+9\)    

\(0=36x^2-36x+9-x^2-6x-9\)   

\(0=35x^2-42x\)   

\(35x^2-42x=0\)   

\(7x\left(5x-6\right)=0\)   

\(\orbr{\begin{cases}7x=0\\5x-6=0\end{cases}}\)   

\(\orbr{\begin{cases}x=0\\x=\frac{6}{5}\end{cases}}\)

\(2x\left(x^2-25\right)=0\)

\(\Rightarrow\orbr{\begin{cases}2x=0\\x^2-25=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x=\pm5\end{cases}}\)

\(2x\left(3x-5\right)+\left(3x-5\right)=0\)

\(\left(2x+1\right)\left(3x-5\right)=0\)

\(\Rightarrow\orbr{\begin{cases}2x+1=0\\3x-5=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-\frac{1}{2}\\x=\frac{5}{3}\end{cases}}\)

\(9\left(3x-2\right)-x\left(2-3x\right)=0\)

\(9\left(3x-2\right)+x\left(3x-2\right)=0\)

\(\left(9+x\right)\left(3x-2\right)=0\)

\(\Rightarrow\orbr{\begin{cases}9+x=0\\3x-2=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=-9\\x=\frac{2}{3}\end{cases}}\)

\(\left(2x-1\right)^2=25\)

\(\Rightarrow\orbr{\begin{cases}2x-1=5\\2x-1=-5\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=3\\x=-2\end{cases}}\)

\(2x^3-50x=0\)

\(\Leftrightarrow2x\left(x^2-25\right)=0\)

\(\Leftrightarrow x^2-25=0\)

\(\Leftrightarrow x^2=25\)

\(\Leftrightarrow x=\pm5\)

a, \(2\left(x+3\right)-x^2-3x=0\)

\(\Leftrightarrow2\left(x+3\right)-x\left(x+3\right)=0\)

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

\(\Leftrightarrow\left[{}\begin{matrix}2-x=0\\x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-3\end{matrix}\right.\)

Vậy x = 2 hoặc x = -3

b, \(8x^3-50x=0\)

\(\Leftrightarrow2x\left(4x^2-25\right)=0\)

\(\Leftrightarrow2x\left(2x-5\right)\left(2x+5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}2x=0\\2x-5=0\\2x+5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{5}{2}\\x=\dfrac{-5}{2}\end{matrix}\right.\)

Vậy...

1.

a) \(2\left(x+3\right)-x^2-3x=0\)

\(2\left(x+3\right)-\left(x^2+3x\right)=0\)

\(2\left(x+3\right)-x\left(x+3\right)=0\)

\(\left(2-x\right)\left(x+3\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}2-x=0\\x+3=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=2\\x=-3\end{matrix}\right.\)

Vậy x=2 hoặc x=-3

b) \(8x^3-50x=0\)

\(x\left(8x^2-50\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\8x^2-50=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x^2=\dfrac{25}{4}=\left(\pm\dfrac{5}{2}\right)^2\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{5}{2}\\x=\dfrac{-5}{2}\end{matrix}\right.\)

Vậy \(x=0\) hoặc \(x=\dfrac{-5}{2}\) hoặc \(x=\dfrac{5}{2}\)

tik mik nhé !!!

a) \(\left(2x-1\right)^2-25=0\)

\(\left(2x-1\right)^2=0+25=25\)

\(\left(2x-1\right)^2=5^2=\left(-5\right)^2\)

\(\Rightarrow\left[\begin{array}{nghiempt}2x-1=5\\2x-1=-5\end{array}\right.\Rightarrow\left[\begin{array}{nghiempt}2x=6\\2x=-4\end{array}\right.\Rightarrow\left[\begin{array}{nghiempt}x=3\\x=-2\end{array}\right.\)

b) \(8x^3-50x=0\)

\(2x\left(4x^2-25\right)=0\)

\(\Rightarrow\left[\begin{array}{nghiempt}2x=0\\4x^2-25=0\end{array}\right.\Rightarrow\left[\begin{array}{nghiempt}x=0\\4x^2=25\Rightarrow x^2=\frac{25}{4}\Rightarrow\left[\begin{array}{nghiempt}x=\frac{5}{2}\\x=-\frac{5}{2}\end{array}\right.\end{array}\right.\)