Question

[thu hương]

 

Cần gấp

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(\dfrac{2}{3}x\left(x^2-4\right)=0\)

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

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

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

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

=>4(x+2)=0

=>x+2=0

=>x=-2

c: \(6x^3+7x^2+2x=0\)

=>\(x\left(6x^2+7x+2\right)=0\)

=>\(x\left(6x^2+4x+3x+2\right)=0\)

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

=>\(\left[{}\begin{matrix}x=0\\3x+2=0\\2x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-\dfrac{2}{3}\\x=-\dfrac{1}{2}\end{matrix}\right.\)

d: \(x^2+4x=7\)

=>\(x^2+4x+4=11\)

=>\(\left(x+2\right)^2=11\)

=>\(\left[{}\begin{matrix}x+2=\sqrt{11}\\x+2=-\sqrt{11}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{11}-2\\x=-\sqrt{11}-2\end{matrix}\right.\)