Tìm x: 2x(3x + 5) - x(6x - 1) = 33

$$\begin{gathered} ~ Câu 13:\hspace{0.17em}Tìm x: \\ a. 2x\left(3x+5\right)-x\left(6x-1\right)=33 \\ b. \left(x+1\right)\left(x+3\right)-x\left(x+1\right)=7 \\ c. \left(3x-5\right)\left(2x-1\right)-\left(x+2\right)\left(6x-1\right)=0 \\ d. x^2-5x+6=0 \end{gathered}$$

$$\begin{gathered} e. 2x\left(x-3\right)+5\left(3-x\right)=0 \\ f. \left(x^2-4\right)-\left(x-2\right)\left(3-2x\right)=0 \\ g. {\left(2x+5\right)}^2={\left(x+2\right)}^2 \\ h. x^3+27+\left(x+3\right)\left(x-9\right)=0 \end{gathered}$$
$$\begin{gathered} ~ Câu 15: Tìm x, biết: \\ a. 3{\left(x-1\right)}^2+3x\left(x-4\right)+1=0 \\ b. x^2-25=6x-9 \\ c. 7x\left(x-4\right)-x+4=0 \\ d. 9x^2-4-2{\left(3x-2\right)}^2=0 \end{gathered}$$​​