Question

Bài 2. Tìm x, biết:

a/ (x – 4)(x + 4) - x(x + 2) = 0

b/ 3x(x – 2) – x + 2 = 0

c/ 6x - 12x2 = 0

d/ 4x(3 - 14x) + (x – 2)(x + 2) = 0

Answer 1

\(a,\Leftrightarrow x^2-16-x^2-2x=0\\ \Leftrightarrow2x=-16\Leftrightarrow x=-8\\ b,\Leftrightarrow\left(x-2\right)\left(3x-1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{1}{3}\end{matrix}\right.\\ c,\Leftrightarrow6x\left(1-2x\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{2}\end{matrix}\right.\\ d,\Leftrightarrow12x-56x^2+x^2-16=0\\ \Leftrightarrow55x^2-12x+16=0\\ \Delta=144-4\cdot55\cdot16< 0\\ \Leftrightarrow x\in\varnothing\)