4: Решите уравнение: a) $$9x^2 - 100 = 0$$; б) $$(4y - 3)^2 - (2y + 5)^2 = 0$$.

4: Решите уравнение: a) $$9x^2 - 100 = 0 \implies 9x^2 = 100 \implies x^2 = \frac{100}{9} \implies x = \pm \frac{10}{3}$$ б) $$(4y - 3)^2 - (2y + 5)^2 = 0 \implies (4y - 3 - (2y + 5))(4y - 3 + 2y + 5) = 0 \implies (2y - 8)(6y + 2) = 0 \implies y = 4 \text{ or } y = -\frac{1}{3}$$