a) Áp dụng \(A^2-B^2=\left(A-B\right)\left(A+B\right)\)
\(\Rightarrow\left(2x-1-x-3\right)\left(2x-1+x+3\right)=0\)
\(\Rightarrow\left(x-4\right)\left(3x+2\right)=0\)
=> x = 4 hoặc x = -2/3
b) \(\Rightarrow x^3-2x^2-4x+8=0\)
<=> \(\left(x^3-2x^2\right)-\left(4x-8\right)=0\)
<=>\(x^2\left(x-2\right)-4\left(x-2\right)=0\)
<=> \(\left(x-2\right)^2\left(x+2\right)=0\)
=> x = 2 hoặc x = -2