Question

tìm x

a)4x(x-1)=x-1

b)2x^3-50x=0

c)5x(2x-7)-14x=-49

Answer 1

Lời giải:

a) \(4x(x-1)=x-1\)

\(\Leftrightarrow 4x(x-1)-(x-1)=0\Leftrightarrow (x-1)(4x-1)=0\)

\(\Rightarrow \left[\begin{matrix} x-1=0\rightarrow x=1\\ 4x-1=0\rightarrow x=\frac{1}{4}\end{matrix}\right.\)

b) \(2x^3-50x=0\Leftrightarrow 2x(x^-25)=0\)

\(\Leftrightarrow 2x(x-5)(x+5)=0\)

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

c) \(5x(2x-7)-14x=-49\)

\(\Leftrightarrow 5x(2x-7)-7(2x-7)=0\)

\(\Leftrightarrow (5x-7)(2x-7)=0\Rightarrow \left[\begin{matrix} 5x-7=0\rightarrow x=\frac{7}{5}\\ 2x-7=0\rightarrow x=\frac{7}{2}\end{matrix}\right.\)