Question

[Ninh Tran Quang]

Giúp mình mấy câu gạch chân màu đỏ với

Answer 1

[Nguyễn Huy Tú]

Answer 2

[Nguyễn Lê Phước Thịnh]

e) Ta có: \(x^2-4x+5=0\)

\(\Leftrightarrow\left(x-2\right)^2+1=0\)(Vô lý)

f) Ta có: \(x\left(x-2\right)+x-2=0\)

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

\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-1\end{matrix}\right.\)

g) Ta có: 5x(x-3)-x+3=0

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

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{1}{5}\end{matrix}\right.\)

h) Ta có: \(x^3-\dfrac{1}{4}x=0\)

\(\Leftrightarrow x\left(x-\dfrac{1}{2}\right)\left(x+\dfrac{1}{2}\right)=0\)

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

i) Ta có: \(x^2\left(x-3\right)-4x+12=0\)

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

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