a) \(x\left(x+1\right)\left(x+6\right)-x^3=5x\)
\(\Leftrightarrow x\left(x^2+7x+6\right)-x^3=5x\)
\(\Leftrightarrow x^3+7x^2+6x-x^3-5x=0\)
\(\Leftrightarrow7x^2+x=0\)
\(\Leftrightarrow x\left(7x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-\dfrac{1}{7}\end{matrix}\right.\)
c: Đề thiếu vế phải rồi bạn
a: \(x\left(x+1\right)\left(x+6\right)-x^3=5x\)
=>\(x\cdot\left(x^2+7x+6\right)-x^3-5x=0\)
=>\(x^3+7x^2+6x-x^3-5x=0\)
=>\(7x^2+x=0\)
=>x(7x+1)=0
=>\(\left[{}\begin{matrix}x=0\\7x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-\dfrac{1}{7}\end{matrix}\right.\)
b: \(\left(3x-5\right)\left(-5x+7\right)+\left(5x+2\right)\left(3x-2\right)-2=0\)
=>\(-15x^2+21x+25x-35+15x^2-10x+6x-4-2=0\)
=>42x-41=0
=>42x=41
=>\(x=\dfrac{41}{42}\)
