г) $$\frac{x^2-1}{3} - \frac{(x-3)^2}{8} = \frac{(x+3)^2}{4} - 3x$$
Умножим обе части уравнения на 24:
$$8(x^2-1) - 3(x-3)^2 = 6(x+3)^2 - 72x$$
$$8x^2-8 - 3(x^2-6x+9) = 6(x^2+6x+9) - 72x$$
$$8x^2-8 - 3x^2+18x-27 = 6x^2+36x+54 - 72x$$
$$5x^2+18x-35 - 6x^2-36x-54 + 72x= 0$$
$$-x^2+54x-89= 0$$
$$x^2-54x+89= 0$$
$$D = (-54)^2 - 4 \cdot 1 \cdot 89 = 2916 - 356 = 2560$$
$$x_1 = \frac{54 + \sqrt{2560}}{2 \cdot 1} = \frac{54+\sqrt{2560}}{2} = \frac{54+16\sqrt{10}}{2} = 27+8\sqrt{10}$$
$$x_2 = \frac{54 - \sqrt{2560}}{2 \cdot 1} = \frac{54-\sqrt{2560}}{2} = \frac{54-16\sqrt{10}}{2} = 27-8\sqrt{10}$$
Ответ: $$x=27+8\sqrt{10}; x=27-8\sqrt{10}$$