Bài 5:
  1)
     a.
           $$\begin{gathered} \begin{array}{l}2x^2-3x+2(2x-3)=0\\ x\left(2x-3\right)+2\left(x-3\right)=0 \\ \left(x+2\right)(2x-3)=0\end{array} \\ \Rightarrow x+2=0 hoặc 2x-3=0 \\ x =-2 2x =3 \\ x =\frac{3}{2} \\ Vậy x\in \left\{-2 ; \frac{3}{2} \right\} \end{gathered}$$
     b. 
          $$\begin{gathered} x^2-5x-14=0 \\ {x}^2-7x+2x-14=0 \\ x(x-7)+2(x-7)=0 \\ (x+2)(x-7)=0 \\ \Rightarrow x+2=0 hoặc x-7=0 \\ x =-2 x =7 \\ Vậy x\in \left\{-2 ; 7\right\} \end{gathered}$$
  2)
     a)
           $$\begin{gathered} x^2-25-(x+5)=0 \\ (x-5)(x+5)-(x+5)=0 \\ (x+5)(x-5-1)=0 \\ (x+5)(x-4)=0 \\ \Rightarrow x+5=0 hoặc x-4=0 \\ x =-5 x =4 \\ Vậy x\in \left\{-5; 4\right\} \end{gathered}$$